literature review qualitative method

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Qualitative research: literature review .

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Exploring the literature review

Literature review model: 6 steps.

Adapted from The Literature Review , Machi & McEvoy (2009, p. 13).

Your Literature Review

Step 2: search, boolean search strategies, search limiters, ★ ebsco & google drive.

1. Select a Topic

"All research begins with curiosity" (Machi & McEvoy, 2009, p. 14)

Selection of a topic, and fully defined research interest and question, is supervised (and approved) by your professor. Tips for crafting your topic include:

Be specific. Take time to define your interest.
Topic Focus. Fully describe and sufficiently narrow the focus for research.
Academic Discipline. Learn more about your area of research & refine the scope.
Avoid Bias. Be aware of bias that you (as a researcher) may have.
Document your research. Use Google Docs to track your research process.
Research apps. Consider using Evernote or Zotero to track your research.

Consider Purpose

What will your topic and research address?

In The Literature Review: A Step-by-Step Guide for Students , Ridley presents that literature reviews serve several purposes (2008, p. 16-17). Included are the following points:

Historical background for the research;
Overview of current field provided by "contemporary debates, issues, and questions;"
Theories and concepts related to your research;
Introduce "relevant terminology" - or academic language - being used it the field;
Connect to existing research - does your work "extend or challenge [this] or address a gap;"
Provide "supporting evidence for a practical problem or issue" that your research addresses.

★ Schedule a research appointment

At this point in your literature review, take time to meet with a librarian. Why? Understanding the subject terminology used in databases can be challenging. Archer Librarians can help you structure a search, preparing you for step two. How? Contact a librarian directly or use the online form to schedule an appointment. Details are provided in the adjacent Schedule an Appointment box.

2. Search the Literature

Collect & Select Data: Preview, select, and organize

AU Library is your go-to resource for this step in your literature review process. The literature search will include books and ebooks, scholarly and practitioner journals, theses and dissertations, and indexes. You may also choose to include web sites, blogs, open access resources, and newspapers. This library guide provides access to resources needed to complete a literature review.

Books & eBooks: Archer Library & OhioLINK

Databases: scholarly & practitioner journals.

Review the Library Databases tab on this library guide, it provides links to recommended databases for Education & Psychology, Business, and General & Social Sciences.

Expand your journal search; a complete listing of available AU Library and OhioLINK databases is available on the Databases A to Z list . Search the database by subject, type, name, or do use the search box for a general title search. The A to Z list also includes open access resources and select internet sites.

Databases: Theses & Dissertations

Review the Library Databases tab on this guide, it includes Theses & Dissertation resources. AU library also has AU student authored theses and dissertations available in print, search the library catalog for these titles.

Did you know? If you are looking for particular chapters within a dissertation that is not fully available online, it is possible to submit an ILL article request . Do this instead of requesting the entire dissertation.

Newspapers: Databases & Internet

Consider current literature in your academic field. AU Library's database collection includes The Chronicle of Higher Education and The Wall Street Journal . The Internet Resources tab in this guide provides links to newspapers and online journals such as Inside Higher Ed , COABE Journal , and Education Week .

Search Strategies & Boolean Operators

There are three basic boolean operators: AND, OR, and NOT.

Used with your search terms, boolean operators will either expand or limit results. What purpose do they serve? They help to define the relationship between your search terms. For example, using the operator AND will combine the terms expanding the search. When searching some databases, and Google, the operator AND may be implied.

Overview of boolean terms

About the example: Boolean searches were conducted on November 4, 2019; result numbers may vary at a later date. No additional database limiters were set to further narrow search returns.

Database Search Limiters

Database strategies for targeted search results.

Most databases include limiters, or additional parameters, you may use to strategically focus search results. EBSCO databases, such as Education Research Complete & Academic Search Complete provide options to:

Limit results to full text;
Limit results to scholarly journals, and reference available;
Select results source type to journals, magazines, conference papers, reviews, and newspapers
Publication date

Keep in mind that these tools are defined as limiters for a reason; adding them to a search will limit the number of results returned. This can be a double-edged sword. How?

If limiting results to full-text only, you may miss an important piece of research that could change the direction of your research. Interlibrary loan is available to students, free of charge. Request articles that are not available in full-text; they will be sent to you via email.
If narrowing publication date, you may eliminate significant historical - or recent - research conducted on your topic.
Limiting resource type to a specific type of material may cause bias in the research results.

Use limiters with care. When starting a search, consider opting out of limiters until the initial literature screening is complete. The second or third time through your research may be the ideal time to focus on specific time periods or material (scholarly vs newspaper).

★ Truncating Search Terms

Expanding your search term at the root.

Truncating is often referred to as 'wildcard' searching. Databases may have their own specific wildcard elements however, the most commonly used are the asterisk (*) or question mark (?). When used within your search. they will expand returned results.

Asterisk (*) Wildcard

Using the asterisk wildcard will return varied spellings of the truncated word. In the following example, the search term education was truncated after the letter "t."

Explore these database help pages for additional information on crafting search terms.

EBSCO Connect: Searching with Wildcards and Truncation Symbols
EBSCO Connect: Searching with Boolean Operators
EBSCO Connect: EBSCOhost Search Tips
EBSCO Connect: Basic Searching with EBSCO
ProQuest Help: Search Tips
ERIC: How does ERIC search work?

★ EBSCO Databases & Google Drive

Tips for saving research directly to Google drive.

Researching in an EBSCO database?

It is possible to save articles (PDF and HTML) and abstracts in EBSCOhost databases directly to Google drive. Select the Google Drive icon, authenticate using a Google account, and an EBSCO folder will be created in your account. This is a great option for managing your research. If documenting your research in a Google Doc, consider linking the information to actual articles saved in drive.

EBSCO Databases & Google Drive

EBSCOHost Databases & Google Drive: Managing your Research

This video features an overview of how to use Google Drive with EBSCO databases to help manage your research. It presents information for connecting an active Google account to EBSCO and steps needed to provide permission for EBSCO to manage a folder in Drive.

About the Video: Closed captioning is available, select CC from the video menu. If you need to review a specific area on the video, view on YouTube and expand the video description for access to topic time stamps. A video transcript is provided below.

EBSCOhost Databases & Google Scholar

Defining Literature Review

What is a literature review.

A definition from the Online Dictionary for Library and Information Sciences .

A literature review is "a comprehensive survey of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works" (Reitz, 2014).

A systemic review is "a literature review focused on a specific research question, which uses explicit methods to minimize bias in the identification, appraisal, selection, and synthesis of all the high-quality evidence pertinent to the question" (Reitz, 2014).

About this page

EBSCO Connect [Discovery and Search]. (2022). Searching with boolean operators. Retrieved May, 3, 2022 from https://connect.ebsco.com/s/?language=en_US

EBSCO Connect [Discover and Search]. (2022). Searching with wildcards and truncation symbols. Retrieved May 3, 2022; https://connect.ebsco.com/s/?language=en_US

Machi, L.A. & McEvoy, B.T. (2009). The literature review . Thousand Oaks, CA: Corwin Press:

Reitz, J.M. (2014). Online dictionary for library and information science. ABC-CLIO, Libraries Unlimited . Retrieved from https://www.abc-clio.com/ODLIS/odlis_A.aspx

Ridley, D. (2008). The literature review: A step-by-step guide for students . Thousand Oaks, CA: Sage Publications, Inc.

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Chapter 9. Reviewing the Literature

What is a “literature review”.

No researcher ever comes up with a research question that is wholly novel. Someone, somewhere, has asked the same thing. Academic research is part of a larger community of researchers, and it is your responsibility, as a member of this community, to acknowledge others who have asked similar questions and to put your particular research into this greater context. It is not simply a convention or custom to begin your study with a review of previous literature (the “ lit review ”) but an important responsibility you owe the scholarly community.

Too often, new researchers pursue a topic to study and then write something like, “No one has ever studied this before” or “This area is underresearched.” It may be that no one has studied this particular group or setting, but it is highly unlikely no one has studied the foundational phenomenon of interest. And that comment about an area being underresearched? Be careful. The statement may simply signal to others that you haven’t done your homework. Rubin ( 2021 ) refers to this as “free soloing,” and it is not appreciated in academic work:

The truth of the matter is, academics don’t really like when people free solo. It’s really bad form to omit talking about the other people who are doing or have done research in your area. Partly, I mean we need to cite their work, but I also mean we need to respond to it—agree or disagree, clarify for extend. It’s also really bad form to talk about your research in a way that does not make it understandable to other academics.…You have to explain to your readers what your story is really about in terms they care about . This means using certain terminology, referencing debates in the literature, and citing relevant works—that is, in connecting your work to something else. ( 51–52 )

A literature review is a comprehensive summary of previous research on a topic. It includes both articles and books—and in some cases reports—relevant to a particular area of research. Ideally, one’s research question follows from the reading of what has already been produced. For example, you are interested in studying sports injuries related to female gymnasts. You read everything you can find on sports injuries related to female gymnasts, and you begin to get a sense of what questions remain open. You find that there is a lot of research on how coaches manage sports injuries and much about cultures of silence around treating injuries, but you don’t know what the gymnasts themselves are thinking about these issues. You look specifically for studies about this and find several, which then pushes you to narrow the question further. Your literature review then provides the road map of how you came to your very specific question, and it puts your study in the context of studies of sports injuries. What you eventually find can “speak to” all the related questions as well as your particular one.

In practice, the process is often a bit messier. Many researchers, and not simply those starting out, begin with a particular question and have a clear idea of who they want to study and where they want to conduct their study but don’t really know much about other studies at all. Although backward, we need to recognize this is pretty common. Telling students to “find literature” after the fact can seem like a purposeless task or just another hurdle for completing a thesis or dissertation. It is not! Even if you were not motivated by the literature in the first place, acknowledging similar studies and connecting your own research to those studies are important parts of building knowledge. Acknowledgment of past research is a responsibility you owe the discipline to which you belong.

Literature reviews can also signal theoretical approaches and particular concepts that you will incorporate into your own study. For example, let us say you are doing a study of how people find their first jobs after college, and you want to use the concept of social capital . There are competing definitions of social capital out there (e.g., Bourdieu vs. Burt vs. Putnam). Bourdieu’s notion is of one form of capital, or durable asset, of a “network of more or less institutionalized relationships of mutual acquaintance or recognition” ( 1984:248 ). Burt emphasizes the “brokerage opportunities” in a social network as social capital ( 1997:355 ). Putnam’s social capital is all about “facilitating coordination and cooperation for mutual benefit” ( 2001:67 ). Your literature review can adjudicate among these three approaches, or it can simply refer to the one that is animating your own research. If you include Bourdieu in your literature review, readers will know “what kind” of social capital you are talking about as well as what kind of social scientist you yourself are. They will likely understand that you are interested more in how some people are advantaged by their social capital relative to others rather than being interested in the mechanics of how social networks operate.

The literature review thus does two important things for you: firstly, it allows you to acknowledge previous research in your area of interest, thereby situating you within a discipline or body of scholars, and, secondly, it demonstrates that you know what you are talking about. If you present the findings of your research study without including a literature review, it can be like singing into the wind. It sounds nice, but no one really hears it, or if they do catch snippets, they don’t know where it is coming from.

Examples of Literature Reviews

To help you get a grasp of what a good literature review looks like and how it can advance your study, let’s take a look at a few examples.

Reader-Friendly Example: The Power of Peers

The first is by Janice McCabe ( 2016 ) and is from an article on peer networks in the journal Contexts . Contexts presents articles in a relatively reader-friendly format, with the goal of reaching a large audience for interesting sociological research. Read this example carefully and note how easily McCabe is able to convey the relevance of her own work by situating it in the context of previous studies:

Scholars who study education have long acknowledged the importance of peers for students’ well-being and academic achievement. For example, in 1961, James Coleman argued that peer culture within high schools shapes students’ social and academic aspirations and successes. More recently, Judith Rich Harris has drawn on research in a range of areas—from sociological studies of preschool children to primatologists’ studies of chimpanzees and criminologists’ studies of neighborhoods—to argue that peers matter much more than parents in how children “turn out.” Researchers have explored students’ social lives in rich detail, as in Murray Milner’s book about high school students, Freaks, Geeks, and Cool Kids , and Elizabeth Armstrong and Laura Hamilton’s look at college students, Paying for the Party . These works consistently show that peers play a very important role in most students’ lives. They tend, however, to prioritize social over academic influence and to use a fuzzy conception of peers rather than focusing directly on friends—the relationships that should matter most for student success. Social scientists have also studied the power of peers through network analysis, which is based on uncovering the web of connections between people. Network analysis involves visually mapping networks and mathematically comparing their structures (such as the density of ties) and the positions of individuals within them (such as how central a given person is within the network). As Nicholas Christakis and James Fowler point out in their book Connected , network structure influences a range of outcomes, including health, happiness, wealth, weight, and emotions. Given that sociologists have long considered network explanations for social phenomena, it’s surprising that we know little about how college students’ friends impact their experiences. In line with this network tradition, I focus on the structure of friendship networks, constructing network maps so that the differences we see across participants are due to the underlying structure, including each participant’s centrality in their friendship group and the density of ties among their friends. ( 23 )

What did you notice? In her very second sentence, McCabe uses “for example” to introduce a study by Coleman, thereby indicating that she is not going to tell you every single study in this area but is going to tell you that (1) there is a lot of research in this area, (2) it has been going on since at least 1961, and (3) it is still relevant (i.e., recent studies are still being done now). She ends her first paragraph by summarizing the body of literature in this area (after giving you a few examples) and then telling you what may have been (so far) left out of this research. In the second paragraph, she shifts to a separate interesting focus that is related to the first but is also quite distinct. Lit reviews very often include two (or three) distinct strands of literature, the combination of which nicely backgrounds this particular study . In the case of our female gymnast study (above), those two strands might be (1) cultures of silence around sports injuries and (2) the importance of coaches. McCabe concludes her short and sweet literature review with one sentence explaining how she is drawing from both strands of the literature she has succinctly presented for her particular study. This example should show you that literature reviews can be readable, helpful, and powerful additions to your final presentation.

Authoritative Academic Journal Example: Working Class Students’ College Expectations

The second example is more typical of academic journal writing. It is an article published in the British Journal of Sociology of Education by Wolfgang Lehmann ( 2009 ):

Although this increase in post-secondary enrolment and the push for university is evident across gender, race, ethnicity, and social class categories, access to university in Canada continues to be significantly constrained for those from lower socio-economic backgrounds (Finnie, Lascelles, and Sweetman 2005). Rising tuition fees coupled with an overestimation of the cost and an underestimation of the benefits of higher education has put university out of reach for many young people from low-income families (Usher 2005). Financial constraints aside, empirical studies in Canada have shown that the most important predictor of university access is parental educational attainment. Having at least one parent with a university degree significantly increases the likelihood of a young person to attend academic-track courses in high school, have high educational and career aspirations, and ultimately attend university (Andres et al. 1999, 2000; Lehmann 2007a). Drawing on Bourdieu’s various writing on habitus and class-based dispositions (see, for example, Bourdieu 1977, 1990), Hodkinson and Sparkes (1997) explain career decisions as neither determined nor completely rational. Instead, they are based on personal experiences (e.g., through employment or other exposure to occupations) and advice from others. Furthermore, they argue that we have to understand these decisions as pragmatic, rather than rational. They are pragmatic in that they are based on incomplete and filtered information, because of the social context in which the information is obtained and processed. New experiences and information can, however, also be allowed into one’s world, where they gradually or radically transform habitus, which in turn creates the possibility for the formation of new and different dispositions. Encountering a supportive teacher in elementary or secondary school, having ambitious friends, or chance encounters can spark such transformations. Transformations can be confirming or contradictory, they can be evolutionary or dislocating. Working-class students who enter university most certainly encounter such potentially transformative situations. Granfield (1991) has shown how initially dislocating feelings of inadequacy and inferiority of working-class students at an elite US law school were eventually replaced by an evolutionary transformation, in which the students came to dress, speak and act more like their middle-class and upper-class peers. In contrast, Lehmann (2007b) showed how persistent habitus dislocation led working-class university students to drop out of university. Foskett and Hemsley-Brown (1999) argue that young people’s perceptions of careers are a complex mix of their own experiences, images conveyed through adults, and derived images conveyed by the media. Media images of careers, perhaps, are even more important for working-class youth with high ambitions as they offer (generally distorted) windows into a world of professional employment to which they have few other sources of access. It has also been argued that working-class youth who do continue to university still face unique, class-specific challenges, evident in higher levels of uncertainty (Baxter and Britton 2001; Lehmann 2004, 2007a; Quinn 2004), their higher education choices (Ball et al. 2002; Brooks 2003; Reay et al. 2001) and fears of inadequacy because of their cultural outsider status (Aries and Seider 2005; Granfield 1991). Although the number of working-class university students in Canada has slowly increased, that of middle-class students at university has risen far more steeply (Knighton and Mizra 2002). These different enrolment trajectories have actually widened the participation gap, which in tum explains our continued concerns with the potential outsider status Indeed, in a study comparing first-generation working-class and traditional students who left university without graduating, Lehmann (2007b) found that first-generation working-class students were more likely to leave university very early in some cases within the first two months of enrollment. They were also more likely to leave university despite solid academic performance. Not “fitting in,” not “feeling university,” and not being able to “relate to these people” were key reasons for eventually withdrawing from university. From the preceding review of the literature, a number of key research questions arise: How do working-class university students frame their decision to attend university? How do they defy the considerable odds documented in the literature to attend university? What are the sources of information and various images that create dispositions to study at university? What role does their social-class background- or habitus play in their transition dispositions and how does this translate into expectations for university? ( 139 )

What did you notice here? How is this different from (and similar to) the first example? Note that rather than provide you with one or two illustrative examples of similar types of research, Lehmann provides abundant source citations throughout. He includes theory and concepts too. Like McCabe, Lehmann is weaving through multiple literature strands: the class gap in higher education participation in Canada, class-based dispositions, and obstacles facing working-class college students. Note how he concludes the literature review by placing his research questions in context.

Find other articles of interest and read their literature reviews carefully. I’ve included two more for you at the end of this chapter . As you learned how to diagram a sentence in elementary school (hopefully!), try diagramming the literature reviews. What are the “different strands” of research being discussed? How does the author connect these strands to their own research questions? Where is theory in the lit review, and how is it incorporated (e.g., Is it a separate strand of its own or is it inextricably linked with previous research in this area)?

One model of how to structure your literature review can be found in table 9.1. More tips, hints, and practices will be discussed later in the chapter.

Table 9.1. Model of Literature Review, Adopted from Calarco (2020:166)

Embracing Theory

A good research study will, in some form or another, use theory. Depending on your particular study (and possibly the preferences of the members of your committee), theory may be built into your literature review. Or it may form its own section in your research proposal/design (e.g., “literature review” followed by “theoretical framework”). In my own experience, I see a lot of graduate students grappling with the requirement to “include theory” in their research proposals. Things get a little squiggly here because there are different ways of incorporating theory into a study (Are you testing a theory? Are you generating a theory?), and based on these differences, your literature review proper may include works that describe, explain, and otherwise set forth theories, concepts, or frameworks you are interested in, or it may not do this at all. Sometimes a literature review sets forth what we know about a particular group or culture totally independent of what kinds of theoretical framework or particular concepts you want to explore. Indeed, the big point of your study might be to bring together a body of work with a theory that has never been applied to it previously. All this is to say that there is no one correct way to approach the use of theory and the writing about theory in your research proposal.

Students are often scared of embracing theory because they do not exactly understand what it is. Sometimes, it seems like an arbitrary requirement. You’re interested in a topic; maybe you’ve even done some research in the area and you have findings you want to report. And then a committee member reads over what you have and asks, “So what?” This question is a good clue that you are missing theory, the part that connects what you have done to what other researchers have done and are doing. You might stumble upon this rather accidentally and not know you are embracing theory, as in a case where you seek to replicate a prior study under new circumstances and end up finding that a particular correlation between behaviors only happens when mediated by something else. There’s theory in there, if you can pull it out and articulate it. Or it might be that you are motivated to do more research on racial microaggressions because you want to document their frequency in a particular setting, taking for granted the kind of critical race theoretical framework that has done the hard work of defining and conceptualizing “microaggressions” in the first place. In that case, your literature review could be a review of Critical Race Theory, specifically related to this one important concept. That’s the way to bring your study into a broader conversation while also acknowledging (and honoring) the hard work that has preceded you.

Rubin ( 2021 ) classifies ways of incorporating theory into case study research into four categories, each of which might be discussed somewhat differently in a literature review or theoretical framework section. The first, the least theoretical, is where you set out to study a “configurative idiographic case” ( 70 ) This is where you set out to describe a particular case, leaving yourself pretty much open to whatever you find. You are not expecting anything based on previous literature. This is actually pretty weak as far as research design goes, but it is probably the default for novice researchers. Your committee members should probably help you situate this in previous literature in some way or another. If they cannot, and it really does appear you are looking at something fairly new that no one else has bothered to research before, and you really are completely open to discovery, you might try using a Grounded Theory approach, which is a methodological approach that foregrounds the generation of theory. In that case, your “theory” section can be a discussion of “Grounded Theory” methodology (confusing, yes, but if you take some time to ponder, you will see how this works). You will still need a literature review, though. Ideally one that describes other studies that have ever looked at anything remotely like what you are looking at—parallel cases that have been researched.

The second approach is the “disciplined configurative case,” in which theory is applied to explain a particular case or topic. You are not trying to test the theory but rather assuming the theory is correct, as in the case of exploring microaggressions in a particular setting. In this case, you really do need to have a separate theory section in addition to the literature review, one in which you clearly define the theoretical framework, including any of its important concepts. You can use this section to discuss how other researchers have used the concepts and note any discrepancies in definitions or operationalization of those concepts. This way you will be sure to design your study so that it speaks to and with other researchers. If everyone who is writing about microaggressions has a different definition of them, it is hard for others to compare findings or make any judgments about their prevalence (or any number of other important characteristics). Your literature review section may then stand alone and describe previous research in the particular area or setting, irrespective of the kinds of theory underlying those studies.

The third approach is “heuristic,” one in which you seek to identify new variables, hypotheses, mechanisms, or paths not yet explained by a theory or theoretical framework. In a way, you are generating new theory, but it is probably more accurate to say that you are extending or deepening preexisting theory. In this case, having a single literature review that is focused on the theory and the ways the theory has been applied and understood (with all its various mechanisms and pathways) is probably your best option. The focus of the literature reviewed is less on the case and more on the theory you are seeking to extend.

The final approach is “theory testing,” which is much rarer in qualitative studies than in quantitative, where this is the default approach. Theory-testing cases are those where a particular case is used to see if an existing theory is accurate or accurate under particular circumstances. As with the heuristic approach, your literature review will probably draw heavily on previous uses of the theory, but you may end up having a special section specifically about cases very close to your own . In other words, the more your study approaches theory testing, the more likely there is to be a set of similar studies to draw on or even one important key study that you are setting your own study up in parallel to in order to find out if the theory generated there operates here.

If we wanted to get very technical, it might be useful to distinguish theoretical frameworks properly from conceptual frameworks. The latter are a bit looser and, given the nature of qualitative research, often fit exploratory studies. Theoretical frameworks rely on specific theories and are essential for theory-testing studies. Conceptual frameworks can pull in specific concepts or ideas that may or may not be linked to particular theories. Think about it this way: A theory is a story of how the world works. Concepts don’t presume to explain the whole world but instead are ways to approach phenomena to help make sense of them. Microaggressions are concepts that are linked to Critical Race Theory. One could contextualize one’s study within Critical Race Theory and then draw various concepts, such as that of microaggressions from the overall theoretical framework. Or one could bracket out the master theory or framework and employ the concept of microaggression more opportunistically as a phenomenon of interest. If you are unsure of what theory you are using, you might want to frame a more practical conceptual framework in your review of the literature.

Helpful Tips

How to maintain good notes for what your read.

Over the years, I have developed various ways of organizing notes on what I read. At first, I used a single sheet of full-size paper with a preprinted list of questions and points clearly addressed on the front side, leaving the second side for more reflective comments and free-form musings about what I read, why it mattered, and how it might be useful for my research. Later, I developed a system in which I use a single 4″ × 6″ note card for each book I read. I try only to use the front side (and write very small), leaving the back for comments that are about not just this reading but things to do or examine or consider based on the reading. These notes often mean nothing to anyone else picking up the card, but they make sense to me. I encourage you to find an organizing system that works for you. Then when you set out to compose a literature review, instead of staring at five to ten books or a dozen articles, you will have ten neatly printed pages or notecards or files that have distilled what is important to know about your reading.

It is also a good idea to store this data digitally, perhaps through a reference manager. I use RefWorks, but I also recommend EndNote or any other system that allows you to search institutional databases. Your campus library will probably provide access to one of these or another system. Most systems will allow you to export references from another manager if and when you decide to move to another system. Reference managers allow you to sort through all your literature by descriptor, author, year, and so on. Even so, I personally like to have the ability to manually sort through my index cards, recategorizing things I have read as I go. I use RefWorks to keep a record of what I have read, with proper citations, so I can create bibliographies more easily, and I do add in a few “notes” there, but the bulk of my notes are kept in longhand.

What kinds of information should you include from your reading? Here are some bulleted suggestions from Calarco ( 2020:113–114 ), with my own emendations:

Citation . If you are using a reference manager, you can import the citation and then, when you are ready to create a bibliography, you can use a provided menu of citation styles, which saves a lot of time. If you’ve originally formatted in Chicago Style but the journal you are writing for wants APA style, you can change your entire bibliography in less than a minute. When using a notecard for a book, I include author, title, date as well as the library call number (since most of what I read I pull from the library). This is something RefWorks is not able to do, and it helps when I categorize.

I begin each notecard with an “intro” section, where I record the aims, goals, and general point of the book/article as explained in the introductory sections (which might be the preface, the acknowledgments, or the first two chapters). I then draw a bold line underneath this part of the notecard. Everything after that should be chapter specific. Included in this intro section are things such as the following, recommended by Calarco ( 2020 ):

Key background . “Two to three short bullet points identifying the theory/prior research on which the authors are building and defining key terms.”
Data/methods . “One or two short bullet points with information about the source of the data and the method of analysis, with a note if this is a novel or particularly effective example of that method.” I use [M] to signal methodology on my notecard, which might read, “[M] Int[erview]s (n-35), B[lack]/W[hite] voters” (I need shorthand to fit on my notecard!).
Research question . “Stated as briefly as possible.” I always provide page numbers so I can go back and see exactly how this was stated (sometimes, in qualitative research, there are multiple research questions, and they cannot be stated simply).
Argument/contributions . “Two to three short bullet points briefly describing the authors’ answer to the central research question and its implication for research, theory, and practice.” I use [ARG] for argument to signify the argument, and I make sure this is prominently visible on my notecard. I also provide page numbers here.

For me, all of this fits in the “intro” section, which, if this is a theoretically rich, methodologically sound book, might take up a third or even half of the front page of my notecard. Beneath the bold underline, I report specific findings or particulars of the book as they emerge chapter by chapter. Calarco’s ( 2020 ) next step is the following:

Key findings . “Three to four short bullet points identifying key patterns in the data that support the authors’ argument.”

All that remains is writing down thoughts that occur upon finishing the article/book. I use the back of the notecard for these kinds of notes. Often, they reach out to other things I have read (e.g., “Robinson reminds me of Crusoe here in that both are looking at the effects of social isolation, but I think Robinson makes a stronger argument”). Calarco ( 2020 ) concludes similarly with the following:

Unanswered questions . “Two to three short bullet points that identify key limitations of the research and/or questions the research did not answer that could be answered in future research.”

As I mentioned, when I first began taking notes like this, I preprinted pages with prompts for “research question,” “argument,” and so on. This was a great way to remind myself to look for these things in particular. You can do the same, adding whatever preprinted sections make sense to you, given what you are studying and the important aspects of your discipline. The other nice thing about the preprinted forms is that it keeps your writing to a minimum—you cannot write more than the allotted space, even if you might want to, preventing your notes from spiraling out of control. This can be helpful when we are new to a subject and everything seems worth recording!

After years of discipline, I have finally settled on my notecard approach. I have thousands of notecards, organized in several index card filing boxes stacked in my office. On the top right of each card is a note of the month/day I finished reading the item. I can remind myself what I read in the summer of 2010 if the need or desire ever arose to do so…those invaluable notecards are like a memento of what my brain has been up to!

Where to Start Looking for Literature

Your university library should provide access to one of several searchable databases for academic books and articles. My own preference is JSTOR, a service of ITHAKA, a not-for-profit organization that works to advance and preserve knowledge and to improve teaching and learning through the use of digital technologies. JSTOR allows you to search by several keywords and to narrow your search by type of material (articles or books). For many disciplines, the “literature” of the literature review is expected to be peer-reviewed “articles,” but some disciplines will also value books and book chapters. JSTOR is particularly useful for article searching. You can submit several keywords and see what is returned, and you can also narrow your search by a particular journal or discipline. If your discipline has one or two key journals (e.g., the American Journal of Sociology and the American Sociological Review are key for sociology), you might want to go directly to those journals’ websites and search for your topic area. There is an art to when to cast your net widely and when to refine your search, and you may have to tack back and forth to ensure that you are getting all that is relevant but not getting bogged down in all studies that might have some marginal relevance.

Some articles will carry more weight than others, and you can use applications like Google Scholar to see which articles have made and are continuing to make larger impacts on your discipline. Find these articles and read them carefully; use their literature review and the sources cited in those articles to make sure you are capturing what is relevant. This is actually a really good way of finding relevant books—only the most impactful will make it into the citations of journals. Over time, you will notice that a handful of articles (or books) are cited so often that when you see, say, Armstrong and Hamilton ( 2015 ), you know exactly what book this is without looking at the full cite. This is when you know you are in the conversation.

You might also approach a professor whose work is broadly in the area of your interest and ask them to recommend one or two “important” foundational articles or books. You can then use the references cited in those recommendations to build up your literature. Just be careful: some older professors’ knowledge of the literature (and I reluctantly add myself here) may be a bit outdated! It is best that the article or book whose references and sources you use to build your body of literature be relatively current.

Keep a List of Your Keywords

When using searchable databases, it is a good idea to keep a list of all the keywords you use as you go along so that (1) you do not needlessly duplicate your efforts and (2) you can more easily adjust your search as you get a better sense of what you are looking for. I suggest you keep a separate file or even a small notebook for this and you date your search efforts.

Here’s an example:

Table 9.2. Keep a List of Your Keywords

Think Laterally

How to find the various strands of literature to combine? Don’t get stuck on finding the exact same research topic you think you are interested in. In the female gymnast example, I recommended that my student consider looking for studies of ballerinas, who also suffer sports injuries and around whom there is a similar culture of silence. It turned out that there was in fact research about my student’s particular questions, just not about the subjects she was interested in. You might do something similar. Don’t get stuck looking for too direct literature but think about the broader phenomenon of interest or analogous cases.

Read Outside the Canon

Some scholars’ work gets cited by everyone all the time. To some extent, this is a very good thing, as it helps establish the discipline. For example, there are a lot of “Bourdieu scholars” out there (myself included) who draw ideas, concepts, and quoted passages from Bourdieu. This makes us recognizable to one another and is a way of sharing a common language (e.g., where “cultural capital” has a particular meaning to those versed in Bourdieusian theory). There are empirical studies that get cited over and over again because they are excellent studies but also because there is an “echo chamber effect” going on, where knowing to cite this study marks you as part of the club, in the know, and so on. But here’s the problem with this: there are hundreds if not thousands of excellent studies out there that fail to get appreciated because they are crowded out by the canon. Sometimes this happens because they are published in “lower-ranked” journals and are never read by a lot of scholars who don’t have time to read anything other than the “big three” in their field. Other times this happens because the author falls outside of the dominant social networks in the field and thus is unmentored and fails to get noticed by those who publish a lot in those highly ranked and visible spaces. Scholars who fall outside the dominant social networks and who publish outside of the top-ranked journals are in no way less insightful than their peers, and their studies may be just as rigorous and relevant to your work, so it is important for you to take some time to read outside the canon. Due to how a person’s race, gender, and class operate in the academy, there is also a matter of social justice and ethical responsibility involved here: “When you focus on the most-cited research, you’re more likely to miss relevant research by women and especially women of color, whose research tends to be under-cited in most fields. You’re also more likely to miss new research, research by junior scholars, and research in other disciplines that could inform your work. Essentially, it is important to read and cite responsibly, which means checking that you’re not just reading and citing the same white men and the same old studies that everyone has cited before you” ( Calarco 2020:112 ).

Consider Multiple Uses for Literature

Throughout this chapter, I’ve referred to the literature of interest in a rather abstract way, as what is relevant to your study. But there are many different ways previous research can be relevant to your study. The most basic use of the literature is the “findings”—for example, “So-and-so found that Canadian working-class students were concerned about ‘fitting in’ to the culture of college, and I am going to look at a similar question here in the US.” But the literature may be of interest not for its findings but theoretically—for example, employing concepts that you want to employ in your own study. Bourdieu’s definition of social capital may have emerged in a study of French professors, but it can still be relevant in a study of, say, how parents make choices about what preschools to send their kids to (also a good example of lateral thinking!).

If you are engaged in some novel methodological form of data collection or analysis, you might look for previous literature that has attempted that. I would not recommend this for undergraduate research projects, but for graduate students who are considering “breaking the mold,” find out if anyone has been there before you. Even if their study has absolutely nothing else in common with yours, it is important to acknowledge that previous work.

Describing Gaps in the Literature

First, be careful! Although it is common to explain how your research adds to, builds upon, and fills in gaps in the previous research (see all four literature review examples in this chapter for this), there is a fine line between describing the gaps and misrepresenting previous literature by failing to conduct a thorough review of the literature. A little humility can make a big difference in your presentation. Instead of “This is the first study that has looked at how firefighters juggle childcare during forest fire season,” say, “I use the previous literature on how working parents juggling childcare and the previous ethnographic studies of firefighters to explore how firefighters juggle childcare during forest fire season.” You can even add, “To my knowledge, no one has conducted an ethnographic study in this specific area, although what we have learned from X about childcare and from Y about firefighters would lead us to expect Z here.” Read more literature review sections to see how others have described the “gaps” they are filling.

Use Concept Mapping

Concept mapping is a helpful tool for getting your thoughts in order and is particularly helpful when thinking about the “literature” foundational to your particular study. Concept maps are also known as mind maps, which is a delightful way to think about them. Your brain is probably abuzz with competing ideas in the early stages of your research design. Write/draw them on paper, and then try to categorize and move the pieces around into “clusters” that make sense to you. Going back to the gymnasts example, my student might have begun by jotting down random words of interest: gymnasts * sports * coaches * female gymnasts * stress * injury * don’t complain * women in sports * bad coaching * anxiety/stress * careers in sports * pain. She could then have begun clustering these into relational categories (bad coaching, don’t complain culture) and simple “event” categories (injury, stress). This might have led her to think about reviewing literature in these two separate aspects and then literature that put them together. There is no correct way to draw a concept map, as they are wonderfully specific to your mind. There are many examples you can find online.

Ask Yourself, “How Is This Sociology (or Political Science or Public Policy, Etc.)?”

Rubin ( 2021:82 ) offers this suggestion instead of asking yourself the “So what?” question to get you thinking about what bridges there are between your study and the body of research in your particular discipline. This is particularly helpful for thinking about theory. Rubin further suggests that if you are really stumped, ask yourself, “What is the really big question that all [fill in your discipline here] care about?” For sociology, it might be “inequality,” which would then help you think about theories of inequality that might be helpful in framing your study on whatever it is you are studying—OnlyFans? Childcare during COVID? Aging in America? I can think of some interesting ways to frame questions about inequality for any of those topics. You can further narrow it by focusing on particular aspects of inequality (Gender oppression? Racial exclusion? Heteronormativity?). If your discipline is public policy, the big questions there might be, How does policy get enacted, and what makes a policy effective? You can then take whatever your particular policy interest is—tax reform, student debt relief, cap-and-trade regulations—and apply those big questions. Doing so would give you a handle on what is otherwise an intolerably vague subject (e.g., What about student debt relief?).

Sometimes finding you are in new territory means you’ve hit the jackpot, and sometimes it means you’ve traveled out of bounds for your discipline. The jackpot scenario is wonderful. You are doing truly innovative research that is combining multiple literatures or is addressing a new or under-examined phenomenon of interest, and your research has the potential to be groundbreaking. Congrats! But that’s really hard to do, and it might be more likely that you’ve traveled out of bounds, by which I mean, you are no longer in your discipline . It might be that no one has written about this thing—at least within your field— because no one in your field actually cares about this topic . ( Rubin 2021:83 ; emphases added)

Don’t Treat This as a Chore

Don’t treat the literature review as a chore that has to be completed, but see it for what it really is—you are building connections to other researchers out there. You want to represent your discipline or area of study fairly and adequately. Demonstrate humility and your knowledge of previous research. Be part of the conversation.

Supplement: Two More Literature Review Examples

Elites by harvey ( 2011 ).

In the last two decades, there has been a small but growing literature on elites. In part, this has been a result of the resurgence of ethnographic research such as interviews, focus groups, case studies, and participant observation but also because scholars have become increasingly interested in understanding the perspectives and behaviors of leaders in business, politics, and society as a whole. Yet until recently, our understanding of some of the methodological challenges of researching elites has lagged behind our rush to interview them.

There is no clear-cut definition of the term elite, and given its broad understanding across the social sciences, scholars have tended to adopt different approaches. Zuckerman (1972) uses the term ultraelites to describe individuals who hold a significant amount of power within a group that is already considered elite. She argues, for example, that US senators constitute part of the country’s political elite but that among them are the ultraelites: a “subset of particularly powerful or prestigious influentials” (160). She suggests that there is a hierarchy of status within elite groups. McDowell (1998) analyses a broader group of “professional elites” who are employees working at different levels for merchant and investment banks in London. She classifies this group as elite because they are “highly skilled, professionally competent, and class-specific” (2135). Parry (1998:2148) uses the term hybrid elites in the context of the international trade of genetic material because she argues that critical knowledge exists not in traditional institutions “but rather as increasingly informal, hybridised, spatially fragmented, and hence largely ‘invisible,’ networks of elite actors.” Given the undertheorization of the term elite, Smith (2006) recognizes why scholars have shaped their definitions to match their respondents . However, she is rightly critical of the underlying assumption that those who hold professional positions necessarily exert as much influence as initially perceived. Indeed, job titles can entirely misrepresent the role of workers and therefore are by no means an indicator of elite status (Harvey 2010).

Many scholars have used the term elite in a relational sense, defining them either in terms of their social position compared to the researcher or compared to the average person in society (Stephens 2007). The problem with this definition is there is no guarantee that an elite subject will necessarily translate this power and authority in an interview setting. Indeed, Smith (2006) found that on the few occasions she experienced respondents wanting to exert their authority over her, it was not from elites but from relatively less senior workers. Furthermore, although business and political elites often receive extensive media training, they are often scrutinized by television and radio journalists and therefore can also feel threatened in an interview, particularly in contexts that are less straightforward to prepare for such as academic interviews. On several occasions, for instance, I have been asked by elite respondents or their personal assistants what they need to prepare for before the interview, which suggests that they consider the interview as some form of challenge or justification for what they do.

In many cases, it is not necessarily the figureheads or leaders of organizations and institutions who have the greatest claim to elite status but those who hold important social networks, social capital, and strategic positions within social structures because they are better able to exert influence (Burt 1992; Parry 1998; Smith 2005; Woods 1998). An elite status can also change, with people both gaining and losing theirs over time. In addition, it is geographically specific, with people holding elite status in some but not all locations. In short, it is clear that the term elite can mean many things in different contexts, which explains the range of definitions. The purpose here is not to critique these other definitions but rather to highlight the variety of perspectives.

When referring to my research, I define elites as those who occupy senior-management- and board-level positions within organizations. This is a similar scope of definition to Zuckerman’s (1972) but focuses on a level immediately below her ultraelite subjects. My definition is narrower than McDowell’s (1998) because it is clear in the context of my research that these people have significant decision-making influence within and outside of the firm and therefore present a unique challenge to interview. I deliberately use the term elite more broadly when drawing on examples from the theoretical literature in order to compare my experiences with those who have researched similar groups.

”Changing Dispositions among the Upwardly Mobile” by Curl, Lareau, and Wu ( 2018 )

There is growing interest in the role of cultural practices in undergirding the social stratification system. For example, Lamont et al. (2014) critically assess the preoccupation with economic dimensions of social stratification and call for more developed cultural models of the transmission of inequality. The importance of cultural factors in the maintenance of social inequality has also received empirical attention from some younger scholars, including Calarco (2011, 2014) and Streib (2015). Yet questions remain regarding the degree to which economic position is tied to cultural sensibilities and the ways in which these cultural sensibilities are imprinted on the self or are subject to change. Although habitus is a core concept in Bourdieu’s theory of social reproduction, there is limited empirical attention to the precise areas of the habitus that can be subject to change during upward mobility as well as the ramifications of these changes for family life.

In Bourdieu’s (1984) highly influential work on the importance of class-based cultural dispositions, habitus is defined as a “durable system of dispositions” created in childhood. The habitus provides a “matrix of perceptions” that seems natural while also structuring future actions and pathways. In many of his writings, Bourdieu emphasized the durability of cultural tastes and dispositions and did not consider empirically whether these dispositions might be changed or altered throughout one’s life (Swartz 1997). His theoretical work does permit the possibility of upward mobility and transformation, however, through the ability of the habitus to “improvise” or “change” due to “new experiences” (Friedman 2016:131). Researchers have differed in opinion on the durability of the habitus and its ability to change (King 2000). Based on marital conflict in cross-class marriages, for instance, Streib (2015) argues that cultural dispositions of individuals raised in working-class families are deeply embedded and largely unchanging. In a somewhat different vein, Horvat and Davis (2011:152) argue that young adults enrolled in an alternative educational program undergo important shifts in their self-perception, such as “self-esteem” and their “ability to accomplish something of value.” Others argue there is variability in the degree to which habitus changes dependent on life experience and personality (Christodoulou and Spyridakis 2016). Recently, additional studies have investigated the habitus as it intersects with lifestyle through the lens of meaning making (Ambrasat et al. 2016). There is, therefore, ample discussion of class-based cultural practices in self-perception (Horvat and Davis 2011), lifestyle (Ambrasat et al. 2016), and other forms of taste (Andrews 2012; Bourdieu 1984), yet researchers have not sufficiently delineated which aspects of the habitus might change through upward mobility or which specific dimensions of life prompt moments of class-based conflict.

Bourdieu (1999:511; 2004) acknowledged simmering tensions between the durable aspects of habitus and those aspects that have been transformed—that is, a “fractured” or “cleft” habitus. Others have explored these tensions as a “divided” or “fragmented” habitus (Baxter and Britton 2001; Lee and Kramer 2013). Each of these conceptions of the habitus implies that changes in cultural dispositions are possible but come with costs. Exploration of the specific aspects of one’s habitus that can change and generate conflict contributes to this literature.

Scholars have also studied the costs associated with academic success for working-class undergraduates (Hurst 2010; Lee and Kramer 2013; London 1989; Reay 2017; Rondini 2016; Stuber 2011), but we know little about the lasting effects on adults. For instance, Lee and Kramer (2013) point to cross-class tensions as family and friends criticize upwardly mobile individuals for their newly acquired cultural dispositions. Documenting the tension many working-class students experience with their friends and families of origin, they find that the source of their pain or struggle is “shaped not only by their interactions with non-mobile family and friends but also within their own minds, by their own assessments of their social positions, and by how those positions are interpreted by others” (Lee and Kramer 2013:29). Hurst (2010) also explores the experiences of undergraduates who have been academically successful and the costs associated with that success. She finds that decisions about “class allegiance and identity” are required aspects of what it means to “becom[e] educated” (4) and that working-class students deal with these cultural changes differently. Jack (2014, 2016) also argues that there is diversity among lower-income students, which yields varied college experiences. Naming two groups, the “doubly disadvantaged” and the “privileged poor,” he argues that previous experience with “elite environments” (2014:456) prior to college informs students’ ability to take on dominant cultural practices, particularly around engagement, such as help seeking or meeting with professors (2016). These studies shed light on the role college might play as a “lever for mobility” (2016:15) and discuss the pain and difficulty associated with upward mobility among undergraduates, but the studies do not illuminate how these tensions unfold in adulthood. Neither have they sufficiently addressed potential enduring tensions with extended family members as well as the specific nature of the difficulties.

Some scholars point to the positive outcomes upwardly mobile youth (Lehmann 2009) and adults (Stuber 2005) experience when they maintain a different habitus than their newly acquired class position, although, as Jack (2014, 2016) shows, those experiences may vary depending on one’s experience with elite environments in their youth. Researchers have not sufficiently explored the specific aspects of the habitus that upwardly mobile adults change or the conflicts that emerge with family and childhood friends as they reach adulthood and experience colliding social worlds. We contribute to this scholarship with clear examples of self-reported changes to one’s cultural dispositions in three specific areas: “horizons,” food and health, and communication. We link these changes to enduring tension with family members, friends, and colleagues and explore varied responses to this tension based on race.

A Guide to Writing a Qualitative Systematic Review Protocol to Enhance Evidence-Based Practice in Nursing and Health Care

Affiliations.

1 PhD candidate, School of Nursing and Midwifey, Monash University, and Clinical Nurse Specialist, Adult and Pediatric Intensive Care Unit, Monash Health, Melbourne, Victoria, Australia.
2 Lecturer, School of Nursing and Midwifery, Monash University, Melbourne, Victoria, Australia.
3 Senior Lecturer, School of Nursing and Midwifery, Monash University, Melbourne, Victoria, Australia.
PMID: 26790142
DOI: 10.1111/wvn.12134

Background: The qualitative systematic review is a rapidly developing area of nursing research. In order to present trustworthy, high-quality recommendations, such reviews should be based on a review protocol to minimize bias and enhance transparency and reproducibility. Although there are a number of resources available to guide researchers in developing a quantitative review protocol, very few resources exist for qualitative reviews.

Aims: To guide researchers through the process of developing a qualitative systematic review protocol, using an example review question.

Methodology: The key elements required in a systematic review protocol are discussed, with a focus on application to qualitative reviews: Development of a research question; formulation of key search terms and strategies; designing a multistage review process; critical appraisal of qualitative literature; development of data extraction techniques; and data synthesis. The paper highlights important considerations during the protocol development process, and uses a previously developed review question as a working example.

Implications for research: This paper will assist novice researchers in developing a qualitative systematic review protocol. By providing a worked example of a protocol, the paper encourages the development of review protocols, enhancing the trustworthiness and value of the completed qualitative systematic review findings.

Linking evidence to action: Qualitative systematic reviews should be based on well planned, peer reviewed protocols to enhance the trustworthiness of results and thus their usefulness in clinical practice. Protocols should outline, in detail, the processes which will be used to undertake the review, including key search terms, inclusion and exclusion criteria, and the methods used for critical appraisal, data extraction and data analysis to facilitate transparency of the review process. Additionally, journals should encourage and support the publication of review protocols, and should require reference to a protocol prior to publication of the review results.

Keywords: guidelines; meta synthesis; qualitative; systematic review protocol.

Evidence-Based Practice / standards*
Information Seeking Behavior
Nursing / methods
Qualitative Research*
Research Design / standards*
Systematic Reviews as Topic*
Writing / standards*

UConn Library
Literature Review: The What, Why and How-to Guide
Introduction

Literature Review: The What, Why and How-to Guide — Introduction

Getting Started
How to Pick a Topic
Strategies to Find Sources
Evaluating Sources & Lit. Reviews
Tips for Writing Literature Reviews
Writing Literature Review: Useful Sites
Citation Resources
Other Academic Writings

What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D. The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review? A literature could be written to accomplish different aims:

To develop a theory or evaluate an existing theory
To summarize the historical or existing state of a research topic
Identify a problem in a field of research

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews . Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

A research paper assigned in a course
A thesis or dissertation
A grant proposal
An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework: 10.1177/08948453211037398

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

Example : The effect of leave policies on increasing fertility: a systematic review: 10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

Example : Employment Instability and Fertility in Europe: A Meta-Analysis: 10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts . Journal of Advanced Nursing , 53 (3), 311-318.

Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis: 10.1177/05390184221113735

Literature Reviews in the Health Sciences

UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
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Last Updated: Sep 21, 2022 2:16 PM
URL: https://guides.lib.uconn.edu/literaturereview

Libraries | Research Guides

Literature reviews, what is a literature review, learning more about how to do a literature review.

Planning the Review
The Research Question
Choosing Where to Search
Organizing the Review
Writing the Review

A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. A literature review should address different aspects of a topic as it relates to your research question. A literature review goes beyond a description or summary of the literature you have read.

Sage Research Methods Core Collection This link opens in a new window SAGE Research Methods supports research at all levels by providing material to guide users through every step of the research process. SAGE Research Methods is the ultimate methods library with more than 1000 books, reference works, journal articles, and instructional videos by world-leading academics from across the social sciences, including the largest collection of qualitative methods books available online from any scholarly publisher. – Publisher

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Last Updated: May 2, 2024 10:39 AM
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Research Methods

Getting Started
Literature Review Research
Research Design
Research Design By Discipline
SAGE Research Methods
Teaching with SAGE Research Methods

Literature Review

What is a Literature Review?
What is NOT a Literature Review?
Purposes of a Literature Review
Types of Literature Reviews
Literature Reviews vs. Systematic Reviews
Systematic vs. Meta-Analysis

Literature Review is a comprehensive survey of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works.

Also, we can define a literature review as the collected body of scholarly works related to a topic:

Summarizes and analyzes previous research relevant to a topic
Includes scholarly books and articles published in academic journals
Can be an specific scholarly paper or a section in a research paper

The objective of a Literature Review is to find previous published scholarly works relevant to an specific topic

Help gather ideas or information
Keep up to date in current trends and findings
Help develop new questions

A literature review is important because it:

Explains the background of research on a topic.
Demonstrates why a topic is significant to a subject area.
Helps focus your own research questions or problems
Discovers relationships between research studies/ideas.
Suggests unexplored ideas or populations
Identifies major themes, concepts, and researchers on a topic.
Tests assumptions; may help counter preconceived ideas and remove unconscious bias.
Identifies critical gaps, points of disagreement, or potentially flawed methodology or theoretical approaches.
Indicates potential directions for future research.

All content in this section is from Literature Review Research from Old Dominion University

Keep in mind the following, a literature review is NOT:

Not an essay

Not an annotated bibliography in which you summarize each article that you have reviewed. A literature review goes beyond basic summarizing to focus on the critical analysis of the reviewed works and their relationship to your research question.

Not a research paper where you select resources to support one side of an issue versus another. A lit review should explain and consider all sides of an argument in order to avoid bias, and areas of agreement and disagreement should be highlighted.

A literature review serves several purposes. For example, it

provides thorough knowledge of previous studies; introduces seminal works.
helps focus one’s own research topic.
identifies a conceptual framework for one’s own research questions or problems; indicates potential directions for future research.
suggests previously unused or underused methodologies, designs, quantitative and qualitative strategies.
identifies gaps in previous studies; identifies flawed methodologies and/or theoretical approaches; avoids replication of mistakes.
helps the researcher avoid repetition of earlier research.
suggests unexplored populations.
determines whether past studies agree or disagree; identifies controversy in the literature.
tests assumptions; may help counter preconceived ideas and remove unconscious bias.

As Kennedy (2007) notes*, it is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the original studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally that become part of the lore of field. In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews.

Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are several approaches to how they can be done, depending upon the type of analysis underpinning your study. Listed below are definitions of types of literature reviews:

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply imbedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to to make summary claims of the sort found in systematic reviews.

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication.

Historical Review Few things rest in isolation from historical precedent. Historical reviews are focused on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [content], but how they said it [method of analysis]. This approach provides a framework of understanding at different levels (i.e. those of theory, substantive fields, research approaches and data collection and analysis techniques), enables researchers to draw on a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection and data analysis, and helps highlight many ethical issues which we should be aware of and consider as we go through our study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyse data from the studies that are included in the review. Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?"

Theoretical Review The purpose of this form is to concretely examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review help establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

* Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147.

All content in this section is from The Literature Review created by Dr. Robert Larabee USC

Robinson, P. and Lowe, J. (2015), Literature reviews vs systematic reviews. Australian and New Zealand Journal of Public Health, 39: 103-103. doi: 10.1111/1753-6405.12393

What's in the name? The difference between a Systematic Review and a Literature Review, and why it matters . By Lynn Kysh from University of Southern California

Systematic review or meta-analysis?

A systematic review answers a defined research question by collecting and summarizing all empirical evidence that fits pre-specified eligibility criteria.

A meta-analysis is the use of statistical methods to summarize the results of these studies.

Systematic reviews, just like other research articles, can be of varying quality. They are a significant piece of work (the Centre for Reviews and Dissemination at York estimates that a team will take 9-24 months), and to be useful to other researchers and practitioners they should have:

clearly stated objectives with pre-defined eligibility criteria for studies
explicit, reproducible methodology
a systematic search that attempts to identify all studies
assessment of the validity of the findings of the included studies (e.g. risk of bias)
systematic presentation, and synthesis, of the characteristics and findings of the included studies

Not all systematic reviews contain meta-analysis.

Meta-analysis is the use of statistical methods to summarize the results of independent studies. By combining information from all relevant studies, meta-analysis can provide more precise estimates of the effects of health care than those derived from the individual studies included within a review. More information on meta-analyses can be found in Cochrane Handbook, Chapter 9 .

A meta-analysis goes beyond critique and integration and conducts secondary statistical analysis on the outcomes of similar studies. It is a systematic review that uses quantitative methods to synthesize and summarize the results.

An advantage of a meta-analysis is the ability to be completely objective in evaluating research findings. Not all topics, however, have sufficient research evidence to allow a meta-analysis to be conducted. In that case, an integrative review is an appropriate strategy.

Some of the content in this section is from Systematic reviews and meta-analyses: step by step guide created by Kate McAllister.

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Literature Reviews

Qualitative or Quantitative?
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Qualitative researchers TEND to:

Researchers using qualitative methods tend to:

t hink that social sciences cannot be well-studied with the same methods as natural or physical sciences
feel that human behavior is context-specific; therefore, behavior must be studied holistically, in situ, rather than being manipulated
employ an 'insider's' perspective; research tends to be personal and thereby more subjective.
do interviews, focus groups, field research, case studies, and conversational or content analysis.

reasons to make a qualitative study; From https://www.editage.com/insights/qualitative-quantitative-or-mixed-methods-a-quick-guide-to-choose-the-right-design-for-your-research?refer-type=infographics

Image from https://www.editage.com/insights/qualitative-quantitative-or-mixed-methods-a-quick-guide-to-choose-the-right-design-for-your-research?refer-type=infographics

Qualitative Research (an operational definition)

Qualitative Research: an operational description

Purpose : explain; gain insight and understanding of phenomena through intensive collection and study of narrative data

Approach: inductive; value-laden/subjective; holistic, process-oriented

Hypotheses: tentative, evolving; based on the particular study

Lit. Review: limited; may not be exhaustive

Setting: naturalistic, when and as much as possible

Sampling : for the purpose; not necessarily representative; for in-depth understanding

Measurement: narrative; ongoing

Design and Method: flexible, specified only generally; based on non-intervention, minimal disturbance, such as historical, ethnographic, or case studies

Data Collection: document collection, participant observation, informal interviews, field notes

Data Analysis: raw data is words/ ongoing; involves synthesis

Data Interpretation: tentative, reviewed on ongoing basis, speculative

Qualitative research with more structure and less subjectivity
Increased application of both strategies to the same study ("mixed methods")
Evidence-based practice emphasized in more fields (nursing, social work, education, and others).

Some Other Guidelines

Guide for formatting Graphs and Tables
Critical Appraisal Checklist for an Article On Qualitative Research

Quantitative researchers TEND to:

Researchers using quantitative methods tend to:

think that both natural and social sciences strive to explain phenomena with confirmable theories derived from testable assumptions
attempt to reduce social reality to variables, in the same way as with physical reality
try to tightly control the variable(s) in question to see how the others are influenced.
Do experiments, have control groups, use blind or double-blind studies; use measures or instruments.

reasons to do a quantitative study. From https://www.editage.com/insights/qualitative-quantitative-or-mixed-methods-a-quick-guide-to-choose-the-right-design-for-your-research?refer-type=infographics

Quantitative Research (an operational definition)

Quantitative research: an operational description

Purpose: explain, predict or control phenomena through focused collection and analysis of numberical data

Approach: deductive; tries to be value-free/has objectives/ is outcome-oriented

Hypotheses : Specific, testable, and stated prior to study

Lit. Review: extensive; may significantly influence a particular study

Setting: controlled to the degree possible

Sampling: uses largest manageable random/randomized sample, to allow generalization of results to larger populations

Measurement: standardized, numberical; "at the end"

Design and Method: Strongly structured, specified in detail in advance; involves intervention, manipulation and control groups; descriptive, correlational, experimental

Data Collection: via instruments, surveys, experiments, semi-structured formal interviews, tests or questionnaires

Data Analysis: raw data is numbers; at end of study, usually statistical

Data Interpretation: formulated at end of study; stated as a degree of certainty

This page on qualitative and quantitative research has been adapted and expanded from a handout by Suzy Westenkirchner. Used with permission.

Images from https://www.editage.com/insights/qualitative-quantitative-or-mixed-methods-a-quick-guide-to-choose-the-right-design-for-your-research?refer-type=infographics.

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What is a theoretical framework?

Developing a theoretical framework for your dissertation is one of the key elements of a qualitative research project. Through writing your literature review, you are likely to have identified either a problem that need ‘fixing’ or a gap that your research may begin to fill.

The theoretical framework is your toolbox . In the toolbox are your handy tools: a set of theories, concepts, ideas and hypotheses that you will use to build a solution to the research problem or gap you have identified.

The methodology is the instruction manual: the procedure and steps you have taken, using your chosen tools, to tackle the research problem.

Why do I need a theoretical framework?

Developing a theoretical framework shows that you have thought critically about the different ways to approach your topic, and that you have made a well-reasoned and evidenced decision about which approach will work best. theoretical frameworks are also necessary for solving complex problems or issues from the literature, showing that you have the skills to think creatively and improvise to answer your research questions. they also allow researchers to establish new theories and approaches, that future research may go on to develop., how do i create a theoretical framework for my dissertation.

First, select your tools. You are likely to need a variety of tools in qualitative research – different theories, models or concepts – to help you tackle different parts of your research question.

An overview of what to include in a theoretical framework: theories, models, ideologies, concepts, assumptions and perspectives.

When deciding what tools would be best for the job of answering your research questions or problem, explore what existing research in your area has used. You may find that there is a ‘standard toolbox’ for qualitative research in your field that you can borrow from or apply to your own research.

You will need to justify why your chosen tools are best for the job of answering your research questions, at what stage they are most relevant, and how they relate to each other. Some theories or models will neatly fit together and appear in the toolboxes of other researchers. However, you may wish to incorporate a model or idea that is not typical for your research area – the ‘odd one out’ in your toolbox. If this is the case, make sure you justify and account for why it is useful to you, and look for ways that it can be used in partnership with the other tools you are using.

You should also be honest about limitations, or where you need to improvise (for example, if the ‘right’ tool or approach doesn’t exist in your area).

This video from the Skills Centre includes an overview and example of how you might create a theoretical framework for your dissertation:

How do I choose the 'right' approach?

When designing your framework and choosing what to include, it can often be difficult to know if you’ve chosen the ‘right’ approach for your research questions. One way to check this is to look for consistency between your objectives, the literature in your framework, and your overall ethos for the research. This means ensuring that the literature you have used not only contributes to answering your research objectives, but that you also use theories and models that are true to your beliefs as a researcher.

Reflecting on your values and your overall ambition for the project can be a helpful step in making these decisions, as it can help you to fully connect your methodology and methods to your research aims.

Should I reflect on my position as a researcher?

If you feel your position as a researcher has influenced your choice of methods or procedure in any way, the methodology is a good place to reflect on this. Positionality acknowledges that no researcher is entirely objective: we are all, to some extent, influenced by prior learning, experiences, knowledge, and personal biases. This is particularly true in qualitative research or practice-based research, where the student is acting as a researcher in their own workplace, where they are otherwise considered a practitioner/professional. It's also important to reflect on your positionality if you belong to the same community as your participants where this is the grounds for their involvement in the research (ie. you are a mature student interviewing other mature learners about their experences in higher education).

The following questions can help you to reflect on your positionality and gauge whether this is an important section to include in your dissertation (for some people, this section isn’t necessary or relevant):

How might my personal history influence how I approach the topic?
How am I positioned in relation to this knowledge? Am I being influenced by prior learning or knowledge from outside of this course?
How does my gender/social class/ ethnicity/ culture influence my positioning in relation to this topic?
Do I share any attributes with my participants? Are we part of a s hared community? How might this have influenced our relationship and my role in interviews/observations?
Am I invested in the outcomes on a personal level? Who is this research for and who will feel the benefits?

One option for qualitative projects is to write an extended literature review. This type of project does not require you to collect any new data. Instead, you should focus on synthesising a broad range of literature to offer a new perspective on a research problem or question.

The main difference between an extended literature review and a dissertation where primary data is collected, is in the presentation of the methodology, results and discussion sections. This is because extended literature reviews do not actively involve participants or primary data collection, so there is no need to outline a procedure for data collection (the methodology) or to present and interpret ‘data’ (in the form of interview transcripts, numerical data, observations etc.) You will have much more freedom to decide which sections of the dissertation should be combined, and whether new chapters or sections should be added.

Here is an overview of a common structure for an extended literature review:

A structure for the extended literature review, showing the results divided into multiple themed chapters.

Introduction

Provide background information and context to set the ‘backdrop’ for your project.
Explain the value and relevance of your research in this context. Outline what do you hope to contribute with your dissertation.
Clarify a specific area of focus.
Introduce your research aims (or problem) and objectives.

Literature review

You will need to write a short, overview literature review to introduce the main theories, concepts and key research areas that you will explore in your dissertation. This set of texts – which may be theoretical, research-based, practice-based or policies – form your theoretical framework. In other words, by bringing these texts together in the literature review, you are creating a lens that you can then apply to more focused examples or scenarios in your discussion chapters.

Methodology

As you will not be collecting primary data, your methodology will be quite different from a typical dissertation. You will need to set out the process and procedure you used to find and narrow down your literature. This is also known as a search strategy.

Including your search strategy

A search strategy explains how you have narrowed down your literature to identify key studies and areas of focus. This often takes the form of a search strategy table, included as an appendix at the end of the dissertation. If included, this section takes the place of the traditional 'methodology' section.

If you choose to include a search strategy table, you should also give an overview of your reading process in the main body of the dissertation. Think of this as a chronology of the practical steps you took and your justification for doing so at each stage, such as:

Your key terms, alternatives and synonyms, and any terms that you chose to exclude.
Your choice and combination of databases;
Your inclusion/exclusion criteria, when they were applied and why. This includes filters such as language of publication, date, and country of origin;
You should also explain which terms you combined to form search phrases and your use of Boolean searching (AND, OR, NOT);
Your use of citation searching (selecting articles from the bibliography of a chosen journal article to further your search).
Your use of any search models, such as PICO and SPIDER to help shape your approach.
Search strategy template A simple template for recording your literature searching. This can be included as an appendix to show your search strategy.

The discussion section of an extended literature review is the most flexible in terms of structure. Think of this section as a series of short case studies or ‘windows’ on your research. In this section you will apply the theoretical framework you formed in the literature review – a combination of theories, models and ideas that explain your approach to the topic – to a series of different examples and scenarios. These are usually presented as separate discussion ‘chapters’ in the dissertation, in an order that you feel best fits your argument.

Think about an order for these discussion sections or chapters that helps to tell the story of your research. One common approach is to structure these sections by common themes or concepts that help to draw your sources together. You might also opt for a chronological structure if your dissertation aims to show change or development over time. Another option is to deliberately show where there is a lack of chronology or narrative across your case studies, by ordering them in a fragmentary order! You will be able to reflect upon the structure of these chapters elsewhere in the dissertation, explaining and defending your decision in the methodology and conclusion.

A summary of your key findings – what you have concluded from your research, and how far you have been able to successfully answer your research questions.

Recommendations – for improvements to your own study, for future research in the area, and for your field more widely.
Emphasise your contributions to knowledge and what you have achieved.

Alternative structure

Depending on your research aims, and whether you are working with a case-study type approach (where each section of the dissertation considers a different example or concept through the lens established in your literature review), you might opt for one of the following structures:

Splitting the literature review across different chapters:

This structure allows you to pull apart the traditional literature review, introducing it little by little with each of your themed chapters. This approach works well for dissertations that attempt to show change or difference over time, as the relevant literature for that section or period can be introduced gradually to the reader.

Whichever structure you opt for, remember to explain and justify your approach. A marker will be interested in why you decided on your chosen structure, what it allows you to achieve/brings to the project and what alternatives you considered and rejected in the planning process. Here are some example sentence starters:

In qualitative studies, your results are often presented alongside the discussion, as it is difficult to include this data in a meaningful way without explanation and interpretation. In the dsicussion section, aim to structure your work thematically, moving through the key concepts or ideas that have emerged from your qualitative data. Use extracts from your data collection - interviews, focus groups, observations - to illustrate where these themes are most prominent, and refer back to the sources from your literature review to help draw conclusions.

Here's an example of how your data could be presented in paragraph format in this section:

Example from 'Reporting and discussing your findings ', Monash University .

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Criteria for Good Qualitative Research: A Comprehensive Review

Regular Article
Open access
Published: 18 September 2021
Volume 31 , pages 679–689, ( 2022 )

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Drishti Yadav ORCID: orcid.org/0000-0002-2974-0323 1

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This review aims to synthesize a published set of evaluative criteria for good qualitative research. The aim is to shed light on existing standards for assessing the rigor of qualitative research encompassing a range of epistemological and ontological standpoints. Using a systematic search strategy, published journal articles that deliberate criteria for rigorous research were identified. Then, references of relevant articles were surveyed to find noteworthy, distinct, and well-defined pointers to good qualitative research. This review presents an investigative assessment of the pivotal features in qualitative research that can permit the readers to pass judgment on its quality and to condemn it as good research when objectively and adequately utilized. Overall, this review underlines the crux of qualitative research and accentuates the necessity to evaluate such research by the very tenets of its being. It also offers some prospects and recommendations to improve the quality of qualitative research. Based on the findings of this review, it is concluded that quality criteria are the aftereffect of socio-institutional procedures and existing paradigmatic conducts. Owing to the paradigmatic diversity of qualitative research, a single and specific set of quality criteria is neither feasible nor anticipated. Since qualitative research is not a cohesive discipline, researchers need to educate and familiarize themselves with applicable norms and decisive factors to evaluate qualitative research from within its theoretical and methodological framework of origin.

Good Qualitative Research: Opening up the Debate

Beyond qualitative/quantitative structuralism: the positivist qualitative research and the paradigmatic disclaimer.

What is Qualitative in Research

Avoid common mistakes on your manuscript.

Introduction

“… It is important to regularly dialogue about what makes for good qualitative research” (Tracy, 2010 , p. 837)

To decide what represents good qualitative research is highly debatable. There are numerous methods that are contained within qualitative research and that are established on diverse philosophical perspectives. Bryman et al., ( 2008 , p. 262) suggest that “It is widely assumed that whereas quality criteria for quantitative research are well‐known and widely agreed, this is not the case for qualitative research.” Hence, the question “how to evaluate the quality of qualitative research” has been continuously debated. There are many areas of science and technology wherein these debates on the assessment of qualitative research have taken place. Examples include various areas of psychology: general psychology (Madill et al., 2000 ); counseling psychology (Morrow, 2005 ); and clinical psychology (Barker & Pistrang, 2005 ), and other disciplines of social sciences: social policy (Bryman et al., 2008 ); health research (Sparkes, 2001 ); business and management research (Johnson et al., 2006 ); information systems (Klein & Myers, 1999 ); and environmental studies (Reid & Gough, 2000 ). In the literature, these debates are enthused by the impression that the blanket application of criteria for good qualitative research developed around the positivist paradigm is improper. Such debates are based on the wide range of philosophical backgrounds within which qualitative research is conducted (e.g., Sandberg, 2000 ; Schwandt, 1996 ). The existence of methodological diversity led to the formulation of different sets of criteria applicable to qualitative research.

Among qualitative researchers, the dilemma of governing the measures to assess the quality of research is not a new phenomenon, especially when the virtuous triad of objectivity, reliability, and validity (Spencer et al., 2004 ) are not adequate. Occasionally, the criteria of quantitative research are used to evaluate qualitative research (Cohen & Crabtree, 2008 ; Lather, 2004 ). Indeed, Howe ( 2004 ) claims that the prevailing paradigm in educational research is scientifically based experimental research. Hypotheses and conjectures about the preeminence of quantitative research can weaken the worth and usefulness of qualitative research by neglecting the prominence of harmonizing match for purpose on research paradigm, the epistemological stance of the researcher, and the choice of methodology. Researchers have been reprimanded concerning this in “paradigmatic controversies, contradictions, and emerging confluences” (Lincoln & Guba, 2000 ).

In general, qualitative research tends to come from a very different paradigmatic stance and intrinsically demands distinctive and out-of-the-ordinary criteria for evaluating good research and varieties of research contributions that can be made. This review attempts to present a series of evaluative criteria for qualitative researchers, arguing that their choice of criteria needs to be compatible with the unique nature of the research in question (its methodology, aims, and assumptions). This review aims to assist researchers in identifying some of the indispensable features or markers of high-quality qualitative research. In a nutshell, the purpose of this systematic literature review is to analyze the existing knowledge on high-quality qualitative research and to verify the existence of research studies dealing with the critical assessment of qualitative research based on the concept of diverse paradigmatic stances. Contrary to the existing reviews, this review also suggests some critical directions to follow to improve the quality of qualitative research in different epistemological and ontological perspectives. This review is also intended to provide guidelines for the acceleration of future developments and dialogues among qualitative researchers in the context of assessing the qualitative research.

The rest of this review article is structured in the following fashion: Sect. Methods describes the method followed for performing this review. Section Criteria for Evaluating Qualitative Studies provides a comprehensive description of the criteria for evaluating qualitative studies. This section is followed by a summary of the strategies to improve the quality of qualitative research in Sect. Improving Quality: Strategies . Section How to Assess the Quality of the Research Findings? provides details on how to assess the quality of the research findings. After that, some of the quality checklists (as tools to evaluate quality) are discussed in Sect. Quality Checklists: Tools for Assessing the Quality . At last, the review ends with the concluding remarks presented in Sect. Conclusions, Future Directions and Outlook . Some prospects in qualitative research for enhancing its quality and usefulness in the social and techno-scientific research community are also presented in Sect. Conclusions, Future Directions and Outlook .

For this review, a comprehensive literature search was performed from many databases using generic search terms such as Qualitative Research , Criteria , etc . The following databases were chosen for the literature search based on the high number of results: IEEE Explore, ScienceDirect, PubMed, Google Scholar, and Web of Science. The following keywords (and their combinations using Boolean connectives OR/AND) were adopted for the literature search: qualitative research, criteria, quality, assessment, and validity. The synonyms for these keywords were collected and arranged in a logical structure (see Table 1 ). All publications in journals and conference proceedings later than 1950 till 2021 were considered for the search. Other articles extracted from the references of the papers identified in the electronic search were also included. A large number of publications on qualitative research were retrieved during the initial screening. Hence, to include the searches with the main focus on criteria for good qualitative research, an inclusion criterion was utilized in the search string.

From the selected databases, the search retrieved a total of 765 publications. Then, the duplicate records were removed. After that, based on the title and abstract, the remaining 426 publications were screened for their relevance by using the following inclusion and exclusion criteria (see Table 2 ). Publications focusing on evaluation criteria for good qualitative research were included, whereas those works which delivered theoretical concepts on qualitative research were excluded. Based on the screening and eligibility, 45 research articles were identified that offered explicit criteria for evaluating the quality of qualitative research and were found to be relevant to this review.

Figure 1 illustrates the complete review process in the form of PRISMA flow diagram. PRISMA, i.e., “preferred reporting items for systematic reviews and meta-analyses” is employed in systematic reviews to refine the quality of reporting.

PRISMA flow diagram illustrating the search and inclusion process. N represents the number of records

Criteria for Evaluating Qualitative Studies

Fundamental criteria: general research quality.

Various researchers have put forward criteria for evaluating qualitative research, which have been summarized in Table 3 . Also, the criteria outlined in Table 4 effectively deliver the various approaches to evaluate and assess the quality of qualitative work. The entries in Table 4 are based on Tracy’s “Eight big‐tent criteria for excellent qualitative research” (Tracy, 2010 ). Tracy argues that high-quality qualitative work should formulate criteria focusing on the worthiness, relevance, timeliness, significance, morality, and practicality of the research topic, and the ethical stance of the research itself. Researchers have also suggested a series of questions as guiding principles to assess the quality of a qualitative study (Mays & Pope, 2020 ). Nassaji ( 2020 ) argues that good qualitative research should be robust, well informed, and thoroughly documented.

Qualitative Research: Interpretive Paradigms

All qualitative researchers follow highly abstract principles which bring together beliefs about ontology, epistemology, and methodology. These beliefs govern how the researcher perceives and acts. The net, which encompasses the researcher’s epistemological, ontological, and methodological premises, is referred to as a paradigm, or an interpretive structure, a “Basic set of beliefs that guides action” (Guba, 1990 ). Four major interpretive paradigms structure the qualitative research: positivist and postpositivist, constructivist interpretive, critical (Marxist, emancipatory), and feminist poststructural. The complexity of these four abstract paradigms increases at the level of concrete, specific interpretive communities. Table 5 presents these paradigms and their assumptions, including their criteria for evaluating research, and the typical form that an interpretive or theoretical statement assumes in each paradigm. Moreover, for evaluating qualitative research, quantitative conceptualizations of reliability and validity are proven to be incompatible (Horsburgh, 2003 ). In addition, a series of questions have been put forward in the literature to assist a reviewer (who is proficient in qualitative methods) for meticulous assessment and endorsement of qualitative research (Morse, 2003 ). Hammersley ( 2007 ) also suggests that guiding principles for qualitative research are advantageous, but methodological pluralism should not be simply acknowledged for all qualitative approaches. Seale ( 1999 ) also points out the significance of methodological cognizance in research studies.

Table 5 reflects that criteria for assessing the quality of qualitative research are the aftermath of socio-institutional practices and existing paradigmatic standpoints. Owing to the paradigmatic diversity of qualitative research, a single set of quality criteria is neither possible nor desirable. Hence, the researchers must be reflexive about the criteria they use in the various roles they play within their research community.

Improving Quality: Strategies

Another critical question is “How can the qualitative researchers ensure that the abovementioned quality criteria can be met?” Lincoln and Guba ( 1986 ) delineated several strategies to intensify each criteria of trustworthiness. Other researchers (Merriam & Tisdell, 2016 ; Shenton, 2004 ) also presented such strategies. A brief description of these strategies is shown in Table 6 .

It is worth mentioning that generalizability is also an integral part of qualitative research (Hays & McKibben, 2021 ). In general, the guiding principle pertaining to generalizability speaks about inducing and comprehending knowledge to synthesize interpretive components of an underlying context. Table 7 summarizes the main metasynthesis steps required to ascertain generalizability in qualitative research.

Figure 2 reflects the crucial components of a conceptual framework and their contribution to decisions regarding research design, implementation, and applications of results to future thinking, study, and practice (Johnson et al., 2020 ). The synergy and interrelationship of these components signifies their role to different stances of a qualitative research study.

Essential elements of a conceptual framework

In a nutshell, to assess the rationale of a study, its conceptual framework and research question(s), quality criteria must take account of the following: lucid context for the problem statement in the introduction; well-articulated research problems and questions; precise conceptual framework; distinct research purpose; and clear presentation and investigation of the paradigms. These criteria would expedite the quality of qualitative research.

How to Assess the Quality of the Research Findings?

The inclusion of quotes or similar research data enhances the confirmability in the write-up of the findings. The use of expressions (for instance, “80% of all respondents agreed that” or “only one of the interviewees mentioned that”) may also quantify qualitative findings (Stenfors et al., 2020 ). On the other hand, the persuasive reason for “why this may not help in intensifying the research” has also been provided (Monrouxe & Rees, 2020 ). Further, the Discussion and Conclusion sections of an article also prove robust markers of high-quality qualitative research, as elucidated in Table 8 .

Quality Checklists: Tools for Assessing the Quality

Numerous checklists are available to speed up the assessment of the quality of qualitative research. However, if used uncritically and recklessly concerning the research context, these checklists may be counterproductive. I recommend that such lists and guiding principles may assist in pinpointing the markers of high-quality qualitative research. However, considering enormous variations in the authors’ theoretical and philosophical contexts, I would emphasize that high dependability on such checklists may say little about whether the findings can be applied in your setting. A combination of such checklists might be appropriate for novice researchers. Some of these checklists are listed below:

The most commonly used framework is Consolidated Criteria for Reporting Qualitative Research (COREQ) (Tong et al., 2007 ). This framework is recommended by some journals to be followed by the authors during article submission.

Standards for Reporting Qualitative Research (SRQR) is another checklist that has been created particularly for medical education (O’Brien et al., 2014 ).

Also, Tracy ( 2010 ) and Critical Appraisal Skills Programme (CASP, 2021 ) offer criteria for qualitative research relevant across methods and approaches.

Further, researchers have also outlined different criteria as hallmarks of high-quality qualitative research. For instance, the “Road Trip Checklist” (Epp & Otnes, 2021 ) provides a quick reference to specific questions to address different elements of high-quality qualitative research.

Conclusions, Future Directions, and Outlook

This work presents a broad review of the criteria for good qualitative research. In addition, this article presents an exploratory analysis of the essential elements in qualitative research that can enable the readers of qualitative work to judge it as good research when objectively and adequately utilized. In this review, some of the essential markers that indicate high-quality qualitative research have been highlighted. I scope them narrowly to achieve rigor in qualitative research and note that they do not completely cover the broader considerations necessary for high-quality research. This review points out that a universal and versatile one-size-fits-all guideline for evaluating the quality of qualitative research does not exist. In other words, this review also emphasizes the non-existence of a set of common guidelines among qualitative researchers. In unison, this review reinforces that each qualitative approach should be treated uniquely on account of its own distinctive features for different epistemological and disciplinary positions. Owing to the sensitivity of the worth of qualitative research towards the specific context and the type of paradigmatic stance, researchers should themselves analyze what approaches can be and must be tailored to ensemble the distinct characteristics of the phenomenon under investigation. Although this article does not assert to put forward a magic bullet and to provide a one-stop solution for dealing with dilemmas about how, why, or whether to evaluate the “goodness” of qualitative research, it offers a platform to assist the researchers in improving their qualitative studies. This work provides an assembly of concerns to reflect on, a series of questions to ask, and multiple sets of criteria to look at, when attempting to determine the quality of qualitative research. Overall, this review underlines the crux of qualitative research and accentuates the need to evaluate such research by the very tenets of its being. Bringing together the vital arguments and delineating the requirements that good qualitative research should satisfy, this review strives to equip the researchers as well as reviewers to make well-versed judgment about the worth and significance of the qualitative research under scrutiny. In a nutshell, a comprehensive portrayal of the research process (from the context of research to the research objectives, research questions and design, speculative foundations, and from approaches of collecting data to analyzing the results, to deriving inferences) frequently proliferates the quality of a qualitative research.

Prospects : A Road Ahead for Qualitative Research

Irrefutably, qualitative research is a vivacious and evolving discipline wherein different epistemological and disciplinary positions have their own characteristics and importance. In addition, not surprisingly, owing to the sprouting and varied features of qualitative research, no consensus has been pulled off till date. Researchers have reflected various concerns and proposed several recommendations for editors and reviewers on conducting reviews of critical qualitative research (Levitt et al., 2021 ; McGinley et al., 2021 ). Following are some prospects and a few recommendations put forward towards the maturation of qualitative research and its quality evaluation:

In general, most of the manuscript and grant reviewers are not qualitative experts. Hence, it is more likely that they would prefer to adopt a broad set of criteria. However, researchers and reviewers need to keep in mind that it is inappropriate to utilize the same approaches and conducts among all qualitative research. Therefore, future work needs to focus on educating researchers and reviewers about the criteria to evaluate qualitative research from within the suitable theoretical and methodological context.

There is an urgent need to refurbish and augment critical assessment of some well-known and widely accepted tools (including checklists such as COREQ, SRQR) to interrogate their applicability on different aspects (along with their epistemological ramifications).

Efforts should be made towards creating more space for creativity, experimentation, and a dialogue between the diverse traditions of qualitative research. This would potentially help to avoid the enforcement of one's own set of quality criteria on the work carried out by others.

Moreover, journal reviewers need to be aware of various methodological practices and philosophical debates.

It is pivotal to highlight the expressions and considerations of qualitative researchers and bring them into a more open and transparent dialogue about assessing qualitative research in techno-scientific, academic, sociocultural, and political rooms.

Frequent debates on the use of evaluative criteria are required to solve some potentially resolved issues (including the applicability of a single set of criteria in multi-disciplinary aspects). Such debates would not only benefit the group of qualitative researchers themselves, but primarily assist in augmenting the well-being and vivacity of the entire discipline.

To conclude, I speculate that the criteria, and my perspective, may transfer to other methods, approaches, and contexts. I hope that they spark dialog and debate – about criteria for excellent qualitative research and the underpinnings of the discipline more broadly – and, therefore, help improve the quality of a qualitative study. Further, I anticipate that this review will assist the researchers to contemplate on the quality of their own research, to substantiate research design and help the reviewers to review qualitative research for journals. On a final note, I pinpoint the need to formulate a framework (encompassing the prerequisites of a qualitative study) by the cohesive efforts of qualitative researchers of different disciplines with different theoretic-paradigmatic origins. I believe that tailoring such a framework (of guiding principles) paves the way for qualitative researchers to consolidate the status of qualitative research in the wide-ranging open science debate. Dialogue on this issue across different approaches is crucial for the impending prospects of socio-techno-educational research.

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Yadav, D. Criteria for Good Qualitative Research: A Comprehensive Review. Asia-Pacific Edu Res 31 , 679–689 (2022). https://doi.org/10.1007/s40299-021-00619-0

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

An introductory paragraph that explains what your working topic and thesis is
A forecast of key topics or texts that will appear in the review
Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
Critically Evaluate: Mention the strengths and weaknesses of your sources
Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

Summarize the key findings you have taken from the literature and emphasize their significance
Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
Qualitative versus quantitative research
Empirical versus theoretical scholarship
Divide the research by sociological, historical, or cultural sources
Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Literature Reviews

Types of reviews
Getting started

Types of reviews and examples

Choosing a review type.

1. Define your research question
2. Plan your search
3. Search the literature
4. Organize your results
5. Synthesize your findings
6. Write the review
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Meta-analysis
Systematized

Definition:

"A term used to describe a conventional overview of the literature, particularly when contrasted with a systematic review (Booth et al., 2012, p. 265).

Characteristics:

Provides examination of recent or current literature on a wide range of subjects
Varying levels of completeness / comprehensiveness, non-standardized methodology
May or may not include comprehensive searching, quality assessment or critical appraisal

Mitchell, L. E., & Zajchowski, C. A. (2022). The history of air quality in Utah: A narrative review. Sustainability , 14 (15), 9653. doi.org/10.3390/su14159653

Booth, A., Papaioannou, D., & Sutton, A. (2012). Systematic approaches to a successful literature review. London: SAGE Publications Ltd.

"An assessment of what is already known about a policy or practice issue...using systematic review methods to search and critically appraise existing research" (Grant & Booth, 2009, p. 100).

Assessment of what is already known about an issue
Similar to a systematic review but within a time-constrained setting
Typically employs methodological shortcuts, increasing risk of introducing bias, includes basic level of quality assessment
Best suited for issues needing quick decisions and solutions (i.e., policy recommendations)

Learn more about the method:

Khangura, S., Konnyu, K., Cushman, R., Grimshaw, J., & Moher, D. (2012). Evidence summaries: the evolution of a rapid review approach. Systematic reviews, 1 (1), 1-9. https://doi.org/10.1186/2046-4053-1-10

Virginia Commonwealth University Libraries. (2021). Rapid Review Protocol .

Quarmby, S., Santos, G., & Mathias, M. (2019). Air quality strategies and technologies: A rapid review of the international evidence. Sustainability, 11 (10), 2757. https://doi.org/10.3390/su11102757

Grant, M.J. & Booth, A. (2009). A typology of reviews: an analysis of the 14 review types and associated methodologies. Health Information & Libraries Journal , 26(2), 91-108. https://www.doi.org/10.1111/j.1471-1842.2009.00848.x

Developed and refined by the Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre), this review "map[s] out and categorize[s] existing literature on a particular topic, identifying gaps in research literature from which to commission further reviews and/or primary research" (Grant & Booth, 2009, p. 97).

Although mapping reviews are sometimes called scoping reviews, the key difference is that mapping reviews focus on a review question, rather than a topic

Mapping reviews are "best used where a clear target for a more focused evidence product has not yet been identified" (Booth, 2016, p. 14)

Mapping review searches are often quick and are intended to provide a broad overview

Mapping reviews can take different approaches in what types of literature is focused on in the search

Cooper I. D. (2016). What is a "mapping study?". Journal of the Medical Library Association: JMLA , 104 (1), 76–78. https://doi.org/10.3163/1536-5050.104.1.013

Miake-Lye, I. M., Hempel, S., Shanman, R., & Shekelle, P. G. (2016). What is an evidence map? A systematic review of published evidence maps and their definitions, methods, and products. Systematic reviews, 5 (1), 1-21. https://doi.org/10.1186/s13643-016-0204-x

Tainio, M., Andersen, Z. J., Nieuwenhuijsen, M. J., Hu, L., De Nazelle, A., An, R., ... & de Sá, T. H. (2021). Air pollution, physical activity and health: A mapping review of the evidence. Environment international , 147 , 105954. https://doi.org/10.1016/j.envint.2020.105954

Booth, A. (2016). EVIDENT Guidance for Reviewing the Evidence: a compendium of methodological literature and websites . ResearchGate. https://doi.org/10.13140/RG.2.1.1562.9842 .

"A type of review that has as its primary objective the identification of the size and quality of research in a topic area in order to inform subsequent review" (Booth et al., 2012, p. 269).

Main purpose is to map out and categorize existing literature, identify gaps in literature—great for informing policy-making
Search comprehensiveness determined by time/scope constraints, could take longer than a systematic review
No formal quality assessment or critical appraisal

Learn more about the methods :

Arksey, H., & O'Malley, L. (2005) Scoping studies: towards a methodological framework. International Journal of Social Research Methodology , 8 (1), 19-32. https://doi.org/10.1080/1364557032000119616

Levac, D., Colquhoun, H., & O’Brien, K. K. (2010). Scoping studies: Advancing the methodology. Implementation Science: IS, 5, 69. https://doi.org/10.1186/1748-5908-5-69

Example :

Rahman, A., Sarkar, A., Yadav, O. P., Achari, G., & Slobodnik, J. (2021). Potential human health risks due to environmental exposure to nano-and microplastics and knowledge gaps: A scoping review. Science of the Total Environment, 757 , 143872. https://doi.org/10.1016/j.scitotenv.2020.143872

A review that "[compiles] evidence from multiple...reviews into one accessible and usable document" (Grant & Booth, 2009, p. 103). While originally intended to be a compilation of Cochrane reviews, it now generally refers to any kind of evidence synthesis.

Compiles evidence from multiple reviews into one document
Often defines a broader question than is typical of a traditional systematic review

Choi, G. J., & Kang, H. (2022). The umbrella review: a useful strategy in the rain of evidence. The Korean Journal of Pain , 35 (2), 127–128. https://doi.org/10.3344/kjp.2022.35.2.127

Aromataris, E., Fernandez, R., Godfrey, C. M., Holly, C., Khalil, H., & Tungpunkom, P. (2015). Summarizing systematic reviews: Methodological development, conduct and reporting of an umbrella review approach. International Journal of Evidence-Based Healthcare , 13(3), 132–140. https://doi.org/10.1097/XEB.0000000000000055

Rojas-Rueda, D., Morales-Zamora, E., Alsufyani, W. A., Herbst, C. H., Al Balawi, S. M., Alsukait, R., & Alomran, M. (2021). Environmental risk factors and health: An umbrella review of meta-analyses. International Journal of Environmental Research and Public Dealth , 18 (2), 704. https://doi.org/10.3390/ijerph18020704

A meta-analysis is a "technique that statistically combines the results of quantitative studies to provide a more precise effect of the result" (Grant & Booth, 2009, p. 98).

Statistical technique for combining results of quantitative studies to provide more precise effect of results
Aims for exhaustive, comprehensive searching
Quality assessment may determine inclusion/exclusion criteria
May be conducted independently or as part of a systematic review

Berman, N. G., & Parker, R. A. (2002). Meta-analysis: Neither quick nor easy. BMC Medical Research Methodology , 2(1), 10. https://doi.org/10.1186/1471-2288-2-10

Hites R. A. (2004). Polybrominated diphenyl ethers in the environment and in people: a meta-analysis of concentrations. Environmental Science & Technology , 38 (4), 945–956. https://doi.org/10.1021/es035082g

A systematic review "seeks to systematically search for, appraise, and [synthesize] research evidence, often adhering to the guidelines on the conduct of a review" provided by discipline-specific organizations, such as the Cochrane Collaboration (Grant & Booth, 2009, p. 102).

Aims to compile and synthesize all known knowledge on a given topic
Adheres to strict guidelines, protocols, and frameworks
Time-intensive and often takes months to a year or more to complete
The most commonly referred to type of evidence synthesis. Sometimes confused as a blanket term for other types of reviews

Gascon, M., Triguero-Mas, M., Martínez, D., Dadvand, P., Forns, J., Plasència, A., & Nieuwenhuijsen, M. J. (2015). Mental health benefits of long-term exposure to residential green and blue spaces: a systematic review. International Journal of Environmental Research and Public Health , 12 (4), 4354–4379. https://doi.org/10.3390/ijerph120404354

"Systematized reviews attempt to include one or more elements of the systematic review process while stopping short of claiming that the resultant output is a systematic review" (Grant & Booth, 2009, p. 102). When a systematic review approach is adapted to produce a more manageable scope, while still retaining the rigor of a systematic review such as risk of bias assessment and the use of a protocol, this is often referred to as a structured review (Huelin et al., 2015).

Typically conducted by postgraduate or graduate students
Often assigned by instructors to students who don't have the resources to conduct a full systematic review

Salvo, G., Lashewicz, B. M., Doyle-Baker, P. K., & McCormack, G. R. (2018). Neighbourhood built environment influences on physical activity among adults: A systematized review of qualitative evidence. International Journal of Environmental Research and Public Health , 15 (5), 897. https://doi.org/10.3390/ijerph15050897

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Published: 18 May 2024

Quantitative analysis of the effects of essential oil mouthrinses on clinical plaque microbiome: a parallel-group, randomized trial

Kyungrok Min 1 ,
Andrew J. Glowacki 1 ,
Mary Lynn Bosma 1 ,
James A. McGuire 1 ,
Sandy Tian 1 ,
Kathleen McAdoo 1 ,
Alicia DelSasso 1 ,
Tara Fourre 1 ,
Robert J. Gambogi 1 ,
Jeffery Milleman 2 &
Kimberly R. Milleman 2

BMC Oral Health volume 24 , Article number: 578 ( 2024 ) Cite this article

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The rich diversity of microorganisms in the oral cavity plays an important role in the maintenance of oral health and development of detrimental oral health conditions. Beyond commonly used qualitative microbiome metrics, such as relative proportions or diversity, both the species-level identification and quantification of bacteria are key to understanding clinical disease associations. This study reports the first-time application of an absolute quantitative microbiome analysis using spiked DNA standards and shotgun metagenome sequencing to assess the efficacy and safety of product intervention on dental plaque microbiome.

In this parallel-group, randomized clinical trial, essential oil mouthrinses, including LISTERINE® Cool Mint Antiseptic (LCM), an alcohol-containing prototype mouthrinse (ACPM), and an alcohol-free prototype mouthrinse (AFPM), were compared against a hydroalcohol control rinse on clinical parameters and the oral microbiome of subjects with moderate gingivitis. To enable a sensitive and clinically meaningful measure of bacterial abundances, species were categorized according to their associations with oral conditions based on published literature and quantified using known amounts of spiked DNA standards.

Multivariate analysis showed that both LCM and ACPM shifted the dysbiotic microbiome composition of subjects with gingivitis to a healthier state after 4 weeks of twice-daily use, resembling the composition of subjects with clinically healthy oral conditions recruited for observational reference comparison at baseline. The essential oil-containing mouthrinses evaluated in this study showed statistically significant reductions in clinical gingivitis and plaque measurements when compared to the hydroalcohol control rinse after 6 weeks of use.

Conclusions

By establishing a novel quantitative method for microbiome analysis, this study sheds light on the mechanisms of LCM mouthrinse efficacy on oral microbial ecology, demonstrating that repeated usage non-selectively resets a gingivitis-like oral microbiome toward that of a healthy oral cavity.

Trial registration

The trial was registered on ClinicalTrials.gov on 10/06/2021. The registration number is NCT04921371.

Peer Review reports

Advances in DNA sequencing have expanded our understanding of the oral microbiome with its site-specific composition and strong associations with oral health conditions [ 1 , 2 , 3 ]. According to the Human Oral Microbiome Database (HOMD), approximately 775 bacterial species reside in the oral cavity, 57% of which are officially named, 13% unnamed but cultivated, and 30% uncultivated phylotypes (eHOMD: http://www.homd.org/ ). Microbial communities at sites where dental plaque is inaccessible, like interproximal sites, show greater diversity of gingivitis and caries-associated bacteria [ 4 ]. Elevated microbial diversity on the tongue is also correlated with an increased representation of malodor-associated bacteria [ 5 ]. The salivary microbiome is representative of various oral microenvironments and can be a useful diagnostic indicator of oral health conditions [ 6 ] like gingivitis, periodontitis, and caries [ 7 ] as well as systemic health conditions [ 8 ]. Beyond microbial heterogeneity, the overall abundance of microorganisms plays a critical role in the development and progression of oral diseases. In a healthy mouth, predominant commensal and less abundant pathogenic species exist in a stable ecological equilibrium. Disruption of this balance occurs in the absence or lapse of oral hygiene, leading to dysbiosis, a shift towards an increasingly pathogenic microbial composition [ 2 , 9 ].

16S rRNA sequencing is a common microbiome profiling approach. Amplification of bacterial 16S ribosomal genes provides high-throughput identification of bacteria via DNA sequence alignment against reference databases. Although this technique detects a wide range of bacterial taxa, it is not able to confidently provide taxonomic identification beyond the genus level [ 10 ]. Alternatively, shallow shotgun metagenomic sequencing (SMS) allows for a complete read of the metagenome, consisting of all DNA, both host and microbe, isolated from a sample. With SMS, DNA is randomly broken into smaller fragments, sequenced, and digitally reassembled by aligning overlapping regions. SMS provides more accurate species-level taxonomic and functional profiles of the microbiome than 16S sequencing [ 11 ]. However, both methods only generate relative abundance data, delivering difficult to interpret results when comparing sample groups.

Quantifying bacterial cell numbers using DNA-based microbiome profiling can elucidate the complex roles microbiomes play in health and disease. Although various methods have been developed to enable the use of relative abundance data [ 12 ], only a few methods can quantify the absolute numbers of bacterial cells [ 13 , 14 ]. Jian et al. have shown that the product of each sample’s total microbial abundance, determined using quantitative polymerase chain reaction (qPCR), against the relative proportions of each bacteria derived from 16S amplicon sequencing, can provide a simple approximation of bacterial cell numbers [ 13 ]. Stammler et al. employed a “spike-in” approach, where controlled amounts of reference DNA from bacteria not normally found in humans were intentionally added in collected specimens prior to sample processing [ 14 ]. These “spiked” reference DNAs help to preserve the absolute quantitative microbiological information present in specimens which are otherwise lost due to the multiple DNA amplification events occurring during sample library preparation. Using the linear regression of input spike-in DNA, taxonomic read counts and genome molecular weights, this method enables the caculation of individual bacterial cell numbers.

In the present study, we combined the enhanced species-level identification capability of SMS with spike-in DNA quantification to assess the impact of essential oil (EO)-containing mouthrinses on the oral plaque microbiome. Three EO-containing mouthrinses, including LISTERINE ® COOL MINT ® (LCM), an alcohol- and EO-containing prototype mouthrinse (ACPM), and an alcohol-free EO prototype mouthrinse (AFPM), were evaluated in subjects with gingivitis for a period of 6 weeks, and then the microbiome of individuals with gingivitis was compared with that of a healthy cohort. To enable measurement of the impacts of oral care products on the clinical plaque microbiome, a literature search was conducted to categorize oral bacteria into commensals, associated with oral health, and pathogens, associated with gingivitis, caries, and malodor. This process of species mapping from the microbiome profiling data with oral health conditions enabled the acquisition of quantitative microbiological results that directly reflect the clinical efficacies of antimicrobial mouthrinses.

Study design

This randomized, controlled, examiner-blind, single-center, parallel-group clinical trial was conducted between October and December 2019 by Salus Research Inc. (Fort Wayne, IN, USA). Subjects in good periodontal health and those with moderate gingivitis were enrolled according to the inclusion/exclusion criteria. At baseline, after abstaining from oral hygiene for at least 8 h, but no more than 18 h, prescreened subjects were given an oral examination of hard and soft tissues and gingivitis and plaque assessments. Periodontally healthy subjects participated only in one baseline assessment. Subjects with moderate gingivitis were randomized to one of four mouthrinses: commercially available US alcohol- and EO-containing LCM as benchmark reference (0.092% eucalyptol, 0.042% menthol, 0.060% methyl salicylate, and 0.064% thymol, 21.6% alcohol) (Johnson & Johnson Consumer Inc., NJ, USA); prototype EO mouthrinses with new sensorial flavor containing alcohol ACPM (0.092% eucalyptol, 0.042% menthol, 0.060% methyl salicylate, and 0.064% thymol, 21.6% alcohol) or without alcohol AFPM (0.092% eucalyptol, 0.042% menthol, 0.060% methyl salicylate, and 0.064% thymol); or a negative control rinse containing 5% hydroalcohol (HA) without any EOs (Fig. 1 ) [ 15 , 16 ]. Subjects were given a fluoridated toothpaste (Colgate ® Cavity Protection, Colgate-Palmolive Company, NY, USA) and standard soft-bristled toothbrushes. They were instructed to brush twice daily (morning and evening) and to rinse for 30 s with 20 mL of an assigned mouthrinse twice daily for 6 weeks. Clinical assessments, including an oral soft tissue evaluation (OST), the Modified Gingival Index (MGI), Expanded Gingival Bleeding Index (EBI), and six-site Turesky modification of the Quigly-Hein Plaque Index (TPI), were completed at weeks 4 and 6. The primary efficacy endpoints were mean MGI and mean TPI at week 6, and the secondary efficacy endpoints were mean MGI, mean TPI at week 4, and mean EBI and percent bleeding sites at weeks 4 and 6. Supragingival plaque was collected 4–6 h after the first brushing and mouthrinse use at weeks 1, 4, and 6 for exploratory microbiome analysis which was the focus of this publication. All clinical assessments in this trial were performed by the same dental examiners who were trained and calibrated with visual assessment of gingival inflammation, supragingival plaque, and gingival bleeding as measured by MGI, TPI, and EBI.

Study design flow chart. ACPM alcohol-containing prototype mouthrinse, AFPM alcohol-free prototype mouthrinse, LCM LISTERINE® COOL MINT. Four patients dropped out of the trial; among them, two withdrew consent, and two were non-compliant

Healthy adults (≥ 18 years of age) with a minimum of 20 natural teeth, including four molars with scorable facial and lingual surfaces, were included. Specific requirements for the healthy reference subjects included: a whole-mouth mean gingivitis score ≤ 0.75 in the MGI [ 17 ], a whole-mouth mean percentage bleeding sites ≤ 3% in the EBI [ 18 ], and no teeth with periodontal pocket depths (PPDs) exceeding 3 mm [ 19 , 20 , 21 ]. Specific requirements for the randomized subjects with moderate gingivitis included a whole-mouth mean gingivitis score ≥ 1.95 in the MGI, a whole-mouth mean plaque score ≥ 1.95 in the TPI [ 22 , 23 ], a whole-mouth mean percentage bleeding sites ≥ 10% in the EBI, and ≤ 3 sites with PPDs exceeding 5 mm [ 24 ]. Key exclusion criteria were the regular use of chemotherapeutic oral care products; antibiotic, anti-inflammatory, or anticoagulant therapy or professional dental cleaning within 4 weeks prior to baseline; history of significant adverse effects, including allergies after use of oral hygiene products or sensitivity to investigational product ingredients; use of intraoral devices; pregnancy; substance abuse; and participation in any clinical trial within 30 days.

Clinical assessments

All examinations were conducted in the following order: an OST, the MGI, EBI, plaque collection for microbiome analysis, and TPI. Gingivitis was assessed using the MGI on the buccal and lingual marginal gingiva and interdental papillae of all scorable teeth as follows: 0–normal (absence of inflammation); 1–mild inflammation of any portion of the entire gingival unit; 2–mild inflammation of the entire gingival unit; 3–moderate inflammation of the gingival unit; and 4–severe inflammation of the gingival unit.

Gingival bleeding was assessed according to the EBI, 168 Sites, by inserting a periodontal probe into the gingival crevice and sweeping from distal to mesial around the tooth at an approximate angle of 60°, while in contact with the sulcular epithelium. Each of six gingival areas (distobuccal, midbuccal, mesiobuccal, distolingual, midlingual, and mesiolingual) around each tooth was assessed. After approximately 30 s, bleeding was recorded at each gingival unit according to the following scale: 0–absence of bleeding after 30 s; 1–bleeding after 30 s; and 2–immediate bleeding.

Plaque was assessed by the TPI to include six surfaces (distobuccal, midbuccal, mesiobuccal, distolingual, midlingual, and mesiolingual) of all scorable teeth as follows: 0–no plaque; 1–separate flecks or discontinuous band of plaque around the gingival margin; 2–up to 1 mm continuous band of plaque at the gingival margin; 3–band of plaque wider than 1 mm but less than 1/3 of the surface; 4–plaque covering 1/3 or more, but less than 2/3 of the surface; and 5–plaque covering 2/3 or more of the surface. Safety was assessed via oral examinations at all exam visits to monitor oral soft and hard tissue tolerance to the treatments and via adverse event collection.

Sample size, treatment allocation, randomization, and blinding

A sample size determination showed that 30 subjects were required per group using a standardized effect size of 0.75 based on previous studies (the difference between treatment population means divided by the population standard deviation) for a two-sided test at the 5% significance level and at 80% power. Assuming a 5% drop-out rate, the trial recruited 32 subjects per group or 128 subjects with moderate gingivitis to ensure trial completion with 120 subjects in the randomized treatment group. Additional 32 subjects in good periodontal health were enrolled, representing the healthy reference group for a baseline assessment only. The randomization schedule for subjects with moderate gingivitis was generated using a validated program created by the Biostatistics Department at Johnson & Johnson Consumer Inc. (Skillman, NJ, USA). Subjects were assigned in an equal allocation to each treatment using a block randomization with a block size of four and were assigned a unique randomization number that sequentially determined the treatment assignment at the baseline visit. To minimize bias, the principal investigator and examiners were blinded to the administered treatments, while the clinical personnel dispensing test products or supervising their use were excluded from subject examinations.

Plaque sample collection

Supragingival plaque was collected for analysis of the microbiome composition prior to plaque staining with a disclosing dye. Plaque samples were collected from four teeth using a sterile curette by moving supragingivally from the mesiobuccal gingival margin to midbuccal, from distobuccal to midbuccal, and then repeated on the lingual side. For each individual subject, plaque samples were pooled and placed in 250 µL of sterile ultra-pure grade phosphate-buffered saline, pH 7.2, and then stored at − 80 °C. The preferentially sampled teeth were the upper right first molar, upper right lateral incisor, lower left second molar, and lower left lateral incisor, which also met the inclusion and exclusion criteria for periodontally healthy subjects versus subjects with moderate gingivitis. Adjacent teeth that met the selection criteria were used as substitutes if the teeth were missing.

Shotgun metagenomic sequencing

DNA isolation, library preparation, and sequencing were carried out at CosmosID (Germantown, MD) using a vendor-optimized protocol. Briefly, plaque samples were spiked with Truepera radiovictrix, Imtechella halotolerans , and Allobacillus halotolerans using ZymoBIOMICS Spike-in Control II (Zymo Research, Irvine, CA) to enable bacterial cell number quantification. To enhance bacterial cell lysis, plaque samples were incubated with MetaPolyzyme at 35 °C for 12 h, and DNA was extracted employing the ZymoBIOMICS DNA MicroPrep with bead-beating according to the manufacturer’s instructions. The concentration of all DNA samples and libraries were determined using the Qubit dsDNA HS assay and Qubit 4 fluorometer (ThermoFisher Scientific, Waltham, MA). To construct DNA libraries, 1 ng of input genomic DNA was fragmented, amplified, and indexed utilizing Nextera XT DNA Library Preparation and Nextera Indexing Kit (Illumina, San Diego, CA). DNA libraries were purified using AMPure magnetic beads (Beckman Coulter, Brea, CA) and then normalized for equimolar pooling. Sequencing was performed with a HiSeq sequencer (Illumina), targeting a coverage of 3 − 4 million paired-end 2 × 150 bp reads.

Statistical analysis of clinical results

Subject demographic and baseline characteristics, including clinical assessment scores (MGI, TPI, and EBI), were compared across treatment groups using analysis of variance (ANOVA), Chi-square test, or Fisher’s exact test. Efficacy analysis was based on the full analysis set following the Intent-to-Treat principle. No imputation of missing data was performed. Statistical comparisons for primary and secondary clinical efficacy endpoints were carried out using a repeated measures mixed model, including terms for treatment and visit and the corresponding baseline value as a covariate.

Computational microbiome analysis

To enable bacterial cell number quantification, plaque samples were spiked with ZymoBIOMICS Spike-in Control II (Zymo Research, Irvine, CA). Raw sequence reads were processed, quality filtered and taxonomically assigned by CosmosID Inc (Germantown, MD). Bacterial diversity analyses were performed using R-3.6.1 [ 25 ]. Alpha-diversity metrics were assessed utilizing vegan 2.5.6 [ 26 ] and included observed richness and Shannon-Weaver diversity indices at the species taxonomic level. Statistical significance was tested using mixed model repeated measures with a baseline covariate and terms for treatment, visit, treatment-by-visit and baseline-by-visit, and unstructured within-subject covariance.

Beta-diversity analysis was performed using phyloseq 1.28.0 [ 27 ] to compute the phylogenetic distance matrix by the weighted UniFrac [ 28 ] for ordination utilizing principal coordinate analysis. The input phylogenetic tree was constructed using GenBank based on the data taxonomy table. Significance testing of factors and interactions affecting bacterial compositions was performed employing PERMANOVA [ 29 ] in adonis in vegan [ 26 ].

For quantification of bacterial abundances, standard calibration curves of spike-in bacteria were evaluated for each sample based on the input amount of control DNA against their output relative abundance values. The amount of DNA for each taxon was computed using linear regression of spike-in control DNA for each sample, and bacterial abundances were computed employing the genome molecular weights specific for each taxon from GenBank. The resulting bacterial abundances were expressed in units of calculated microbial units (CMUs) and were represented in log10 where appropriate. For differential abundance testing of individual bacterial species, these log10 abundance values were used in two-sample Wilcoxon rank sum tests comparing healthy vs. gingivitis subjects at baseline or comparing each mouthrinse against the hydroalcohol negative control for week 4 and week 6 visits.

To assess the product impact, bacterial taxa were classified into specific categories based on their association with health conditions: commensals, malodor associated, gingival disease associated, acidogenic, and systemic pathogens. The bacterial classification was assigned based on scientific literature review and annotations from the HOMD [ 30 ]. The abundances of bacterial species associated with these different categories were log10-transformed and pooled per sample, and the means were reported for group comparisons.

Of the 157 subjects enrolled in this clinical trial, four subjects discontinued (Fig. 1 ). Those who completed the trial included 32 subjects in good periodontal health (healthy) and 121 subjects with moderate gingivitis, randomized into four treatment arms: 31 in the LCM group, 29 in the ACPM group, 30 in the alcohol-free EO-containing AFPM group, and 31 in the negative control 5% HA rinse group. The mean (SD) age of the subjects was 43.2 (13.3) years, and the majority were females (74.5%), Caucasian (89.5%), and non-smokers (100%). The overall clinical parameters for healthy subjects at baseline with regards to the mean (SD) MGI, TPI, and EBI were 0.438 (0.115), 2.530 (0.392), and 0.018 (0.013), respectively, whereas, for subjects with moderate gingivitis, these scores were 2.530 (0.255), 3.001 (0.400), and 0.356 (0.191), respectively (Table 1 ).

Clinical efficacy and safety

After twice daily use for 6 weeks, subjects with moderate gingivitis showed significant improvements in clinical signs of gingivitis, plaque, and bleeding in all three treatment groups (Table 2 ). Assessment of gingival inflammation by whole-mouth mean MGI demonstrated that all mouthrinses reduced gingivitis by at least 37.4% compared with HA. Although ACPM demonstrated significant reductions only in MGI after 6 weeks, LCM and AFPM showed significant reductions in MGI earlier, after 4 weeks (Table 2 ). Additionally, LCM and ACPM demonstrated significant reductions in dental plaque by at least 22% after 4 weeks, with further reductions after 6 weeks (Table 2 ). AFPM established a significant 14% plaque reduction after 6 weeks (Table 2 ). Consistent with reductions in gingivitis and plaque, all mouthrinses resulted in a bleeding reduction of at least 36.3% compared with the HA negative control (Table 2 ). All treatments in this trial were well tolerated.

Microbial profiling and mapping to oral health conditions

From the SMS data, 856 unique taxa were identified at the species level. These taxa were classified according to their clinical relevance via extensive clinical and scientific literature review coupled with HOMD data (Table 3 and Additional File 1). Among them, 386 were unclassified, 257 were identified as extraoral bacterial species, and 213 were identified as human oral bacterial species. To enable quantitative microbiome assessment after mouthrinse use, these 213 bacterial species were subdivided according to their oral health-associated outcome, including commensals and those associated with gingivitis, periodontitis, malodor, and caries. There was some species overlap across these different categories (Additional File 1). Therefore, quantification of bacteria associated with specific oral health conditions was confined to each individual category to avoid artificial value inflation.

Short-term and long-term impacts on supragingival plaque microbiome

The accuracy of bacterial cell numbers calculated with the spike-in control approach was evaluated against colony-counting and 16S rRNA qPCR (Table 4 ). The sum of oral bacterial species (Table 3 ) representing the different selectivity of growth media showed similar abundance results to reported colony-counting values (Table 4 ). Bacterial counts reported for 16S qPCR were generally one order of magnitude higher than those for the spike-in approach or colony-counting, likely due to the non-specific detection of total bacterial species including non-culturable, aerobic, transient extra-oral species and non-specific amplicons.

The subjects who participated in this trial maintained reduced levels of plaque bacteria 4–6 h after the initial prophylaxis and first 30 s rinse (Fig. 2 A-C). The reductions observed for the interventions were not significantly different from the known bacterial reduction effects of dental prophylaxis represented by the HA control. A longitudinal assessment of twice daily mouthrinse use on the supragingival plaque microbiota was also performed. Subjects with moderate gingivitis in the LCM and ACPM groups experienced significant reductions in total microbial load (TML) after 1, 4, and 6 weeks (Fig. 3 A). The AFPM group only demonstrated a significant TML reduction after 1 week. The HA negative control group had no significant changes in TML compared to baseline (Fig. 3 A). Analysis of alpha diversity showed the supragingival plaque of subjects in the LCM and ACPM groups had significant reductions in the Shannon-Weaver diversity index after 4 and 6 weeks of mouthrinse use (Fig. 3 B). However, AFPM maintained similar microbial diversity as the HA negative control group. Analysis of the observed richness index showed significant decreases in the number of bacterial species in the LCM and ACPM groups after 6 weeks of mouthrinse use (Fig. 3 C). To better understand the changes occurring in the microbiome composition, the abundance of individual bacterial species at each visit was compared with that at baseline. Log 10 CMU results showed a preponderance of commensal species compared with those associated with clinical signs of gingivitis (Fig. 4 A Baseline Commensal vs. Gingivitis/Periodontitis Species). Furthermore, the TML reduction patterns for subjects assigned to EO mouthrinses were indiscriminate across all bacterial categories. Considering the polymicrobial etiology of oral health issues, the impact of mouthrinse use was also assessed by comparing the sums of bacterial abundances by clinical relevance group (Fig. 4 B-E; Table 5 ). Commensal, gingivitis and halitosis associated species were significantly reduced by twice daily use of LCM or ACPM compared with the HA group after 1, 4, and 6 weeks (Fig. 4 B-E) The AFPM group showed no statistically significant reductions. Furthermore, no significant differences were observed for acidogenic species between the mouthrinse treatments and the HA negative control group, reflecting the clinical trial eligibility criteria that excluded subjects at risk of caries development.

Changes in the total microbial load and diversity of supragingival plaque microbiome in moderate gingivitis 4–6 h after dental prophylaxis and rinsing with a mouthrinse for 30 s. Box plots of the total microbial load A , Shannon-Weaver diversity index B , and observed species richness C are shown. Error bars represent the range of values. *** p < 0.001. ACPM alcohol-containing prototype mouthrinse, AFPM alcohol-free prototype mouthrinse, LCM LISTERINE® COOL MINT, NS non-significant

Time-resolved changes in the microbial load and diversity of supragingival plaque in subjects with moderate gingivitis after twice daily brushing followed by rinsing with a mouthrinse for 30 s. Box plots of the total microbial load A , Shannon-Weaver diversity index B , and observed species richness C are shown. Error bars represent the range of values. * p < 0.05, ** p < 0.01, *** p < 0.001 (mixed model repeated measures with baseline covariate and terms for treatment, visit, treatment-by-visit and baseline-by-visit, and unstructured within-subject covariance). ACPM alcohol-containing prototype mouthrinse, AFPM alcohol-free prototype mouthrinse, LCM Listerine® COOL MINT

Impact of mouthrinse use on different classifications of bacteria in the supragingival plaque of subjects with moderate gingivitis. A Heatmap showing changes in the abundance of individual bacterial species in supragingival plaque of subjects with moderate gingivitis at different time points compared to baseline. Baseline abundance values represent the initial number of bacterial cells at the start of the study expressed as means of log 10 CMUs. Changes in bacterial cell numbers are expressed as means of paired differences in log 10 CMUs at each time point compared to baseline. B Abundance values represent means of total CMUs from bacterial species that are oral commensals or are C associated with gingivitis, D volatile-sulfur compound − producing, E or acidogenic. Subjects with active caries or grossly carious lesions were not included in this trial. Error bars denote the standard error of the mean. ACPM alcohol-containing prototype mouthrinse, AFPM alcohol-free prototype mouthrinse, LCM LISTERINE COOL MINT Antiseptic mouthrinse, D0 Day 0/baseline, W week, 4–6 H 4–6 h after dental prophylaxis and mouthrinse use; W week. * p < 0.05, ** p < 0.01, *** p < 0.001 (mixed model repeated measures with baseline covariate and terms for treatment, visit, treatment-by-visit, and baseline-by-visit)

Return from dysbiosis to healthier levels

The longitudinal impacts on the supragingival plaque microbiome of subjects with moderate gingivitis were compared against the naturally healthy reference cohort at baseline. Analysis of beta diversity showed that the microbiota of subjects with gingivitis were distinct from those of the healthy reference at baseline (Fig. 5 ). Differential abundance testing revealed that several species were significantly more abundant in subjects with gingivitis, including commensals and key pathogens associated with gingivitis, such as Fusobacterium nucleatum, A. actinomycetemcomitans , and Prevotella species (Table 6 ). Comparisons at post-baseline visits demonstrated changes in the microbiome composition of subjects with gingivitis in the LCM and ACPM groups, resembling the healthy cohorts at baseline, whereas the microbiome composition of the AFPM and HA groups resembled that of subjects with gingivitis at baseline (Fig. 5 ). Further examination of individual bacteria abundances showed that many oral bacterial species were significantly reduced to levels comparable or lower than those found in healthy cohorts (Table 5 ).

Time-resolved changes in the beta diversity of supragingival plaque microbiome comparing subjects with moderate gingivitis randomized to different mouthrinse treatment groups against reference cohorts with naturally healthy oral cavities at baseline. Sample ordination was performed with the weighted UniFrac distance computed at the species taxonomic level, using CMUs for bacterial abundance, and graphed in a two-dimensional principal coordinate plot. ACPM alcohol-containing prototype mouthrinse, AFPM alcohol-free prototype mouthrinse, LCM LISTERINE COOL MINT Antiseptic mouthrinse

The unique formulation of Listerine mouthrinses with a fixed combination of EOs (menthol, thymol, eucalyptol, and methyl salicylate) provides a broad-spectrum bactericidal action that is demonstrated to be safe and efficacious over decades of published clinical studies [ 15 , 16 , 37 ]. In this study, we aimed to characterize the effects of EO-containing mouthrinses on the microbiome of oral plaque using a novel method of quantitative analysis that combined the enhanced species-level identification capability of SMS with spike-in DNA quantification. The data from this study provides a sensitive and detailed assessment of the oral microbiome not previously available in studies of oral care products [ 38 , 39 ]. This first-time application of quantitative microbiome analysis describes how the broad-spectrum antimicrobial effects of EOs skew plaque regrowth towards an early colonizing state, and shift the microbiome towards health with repeated use.

All three EO-containing mouthrinses resulted in significant reductions in clinical plaque and gingivitis measurements when compared to the HA control over 6 weeks of use consistent with previously published clinical studies (Table 2 ) [ 15 , 16 , 37 ]. The prototype mouthrinses ACPM and AFPM contained a new sensorial flavor ingredient and were evaluated for comparison against the commerically available reference mouthrinse LCM. The antiplaque effects of the AFPM were not as strong as the alcohol-containing mouthrinses (Table 2 ) in this study. This result can be attributed to differences in the AFPM formulation, likely affecting EO solubility and the excipient’s ability to impact the EOs’ bactericidal action; however, this effect is not likely due to the absence of alcohol. Moreover, previous laboratory studies demonstrated that much higher concentrations of alcohol are needed to exhibit antimicrobial effects [ 40 ]. Despite reduced plaque efficacy, the AFPM showed a strong clinical reduction in gingivitis (Table 2 ), implicating a mechanism outside of plaque control.

SMS increased the number of bacteria identified at the species level compared to 16S sequencing. This enabled mapping of identified species to their source (oral vs. extraoral) and oral health associations (commensal, gingivitis, malodor, caries) allowing for the exclusive analysis of oral bacteria. Given the presence of environmental, contaminating, and taxonomically undefined species in the metagenomic data [ 41 ], bacterial species mapping offered a higher level of specificity during analysis, permitting examination of treatment effects on clinically relevant groups of bacteria (Fig. 4 ). The absolute abundance measures provided by this technique allowed precise examination of the plaque microbiome composition, foregoing the drawbacks of relative abundance. For example, the total quantity of bacteria in a sample could be reduced, while their relative abundances can remain unchanged, or substantial changes in the relative abundance of one taxon can artificially inflate or deflate the remaining taxa in that sample [ 13 , 42 ]. The results become even more confounding when individual sample relative abundances are averaged for group comparisons, which has a significant potential for generating misleading information. Absolute bacterial quantification is less prone to misinterpretation, leading to more meaningful comparisons between the clinical sample groups. This is also demonstrated by our data that conform to historically published results, using selective culture-based, colony-counting, and 16S rRNA qPCR methods (Table 4 ). The quantitative results in this study showed that the microbiota of subjects with moderate gingivitis had greater abundances of commensal and pathogenic species than the healthy cohort (Table 5 ). In future investigations, in-depth analysis of host inflammatory response may provide a more comprehensive understanding of disease progression.

To minimize inter-subject variability, subjects with gingivitis underwent dental prophylaxis after baseline plaque sampling. Microbiological assessment after prophylaxis and first rinse demonstrated reductions in bacterial load, richness, and diversity with no differences between treatment groups (Fig. 2 ). This result showed that dental prophylaxis had a substantial initial impact; however, neither of these interventions eradicated all supragingival plaque bacteria. Previously published clinical studies using colony counting further support that EO-containing mouthrinses cannot impact the entirety of the oral microbiome [ 34 , 35 , 36 , 43 ]. Instead, predominantly early colonizing, health-associated commensals reestablished plaque after repeated use (Fig. 4 ; Table 5 ). Dimensional reduction analysis further corroborated that both LCM and ACPM shifted the gingivitis-associated microbiome towards the health-associated microbiome after 4 weeks of use (Fig. 5 ). In contrast, the microbiome of HA control subjects returned to baseline dysbiosis (Fig. 5 ). This striking result is the first clear demonstration that LCM, when used twice daily for 4 weeks, can revert a gingivitis-associated microbiome towards a healthier state, suggesting a reset of the plaque microbiome towards an early-colonizing state.

By utilizing a quantitative method for microbiome analysis, this study provides a level of clarity and sensitivity not achievable by the widely used 16S sequencing approach. The results of this study reinforce the known clinical efficacy of LCM for reducing plaque and gingivitis; additionally, we show that its microbiological action is not due to selective killing of pathogenic bacteria but rather via a reset mechanism, in which the plaque microbiome composition is shifted to a healthier state after repeated use.

Availability of data and materials

Shotgun metagenomic sequence data and sample metadata information are available in the NCBI BioProject database under accession number PRJNA952827. Bacterial classification data are provided in additional file 1.

Abbreviations

Alcohol-containing prototype mouthrinse

Alcohol-free prototype mouthrinse

Calculated microbial units

Expanded Gingival Bleeding Index

Essential oil

Hydroalcohol

Human Oral Microbiome Database

LISTERINE® Cool Mint Antiseptic

The Modified Gingival Index

Oral soft tissue evaluation

Periodontal pocket depths

Quantitative polymerase chain reaction

Total microbial load

Turesky modification of the Quigly-Hein Plaque Index

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Acknowledgements

The authors acknowledge Marsha Tharakan and Francisco Fields for their assistance with writing and reviewing the manuscript.

This study was funded by Johnson and Johnson Consumer Inc.

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Contributions

MLB, AG, KM, TF, and RJG, contributed to study conception and design. JM and KRM executed the clinical trial. ADS and KMc contributed to clinical protocol writing, trial management, and supervision. KM carried out bioinformatic data processing. KM, ST, JAM, and MLB contributed to data analysis and interpretation. JAM and ST carried out statistical analysis of the results. All authors contributed to the writing and review of the manuscript. All authors read and approved the final manuscript and agree to be accountable for all aspects of the work.

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Correspondence to Kyungrok Min .

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This trial was conducted in accordance with the International Council for Harmonization guidelines for Good Clinical Practice (E6 [R2]). The study protocol, informed consent document, and study materials were reviewed and approved by an independent institutional review board and ethics committee (IntegReview, LLC, Austin, TX). Written informed consent was obtained from all subjects. The CONSORT statement was followed for the reporting of this randomized clinical trial.

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Competing interests

This research was funded by Johnson & Johnson Consumer Inc. and conducted by its research team in partnership with Salus Research Inc. (Fort Wayne, IN), a third-party independent clinical research site qualified by the American Dental Association. Jeffrey Milleman and Kimberly Milleman are directors at Salus Research Inc. and declare no conflicts of interests with respect to the research, authorship, and/or publication of this article. The authors declare no conflict of interest or any direct involvement with study execution that would influence its outcome.

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Min, K., Glowacki, A.J., Bosma, M.L. et al. Quantitative analysis of the effects of essential oil mouthrinses on clinical plaque microbiome: a parallel-group, randomized trial. BMC Oral Health 24 , 578 (2024). https://doi.org/10.1186/s12903-024-04365-9

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v.13(7); 2023
PMC10387734

Application of classic grounded theory in nursing studies: a qualitative systematic review protocol

Justine connor.

1 School of Nursing, Midwifery and Social Sciences, CQUniversity Brisbane, Brisbane, Queensland, Australia

Tracy Flenady

2 School of Nursing, Midwifery and Social Sciences, CQUniversity, Rockhampton, Queensland, Australia

Trudy Dwyer

Debbie massey.

3 School of Nursing and Midwifery, Edith Cowan University, Joondalup, Western Australia, Australia

Associated Data

Introduction.

Classic grounded theory (CGT) is a valuable method for nursing research, but the application of CGT methodology in nursing studies has not been specifically investigated. With the increasing use of CGT in nursing research, attention is now focusing on the quality of studies using this methodology. In this systematic review, we aim to develop an understanding of the application of CGT methodology, specifically appraising the quality of the methodology’s application in the field of nursing research.

Methods and analysis

The reporting of this review will be guided by the Preferred Reporting Items for Systematic and Meta-Analysis guidelines statement and data synthesis guided by the Synthesis Without Meta-analysis guideline. Publications will be uploaded to Rayyan. The quality of each article will be assessed using the Critical Appraisals Skills Programme qualitative research appraisal tool. Analysis of the selected studies will be performed using the Guideline for Reporting and Evaluating Grounded Theory Research Studies, explicitly the CGT guiding principles.

Ethics and dissemination

Ethical approval is not required because only secondary data will be used in this review. The results of the final study will be published in a peer-reviewed open-access journal.

PROSPERO registration number

CRD42021281103.

STRENGTHS AND LIMITATIONS OF THIS STUDY

Strict eligibility criteria have been established for inclusion and exclusion for selecting the primary studies for the review.
The validated tool, the Guideline for Reporting and Evaluating Grounded Theory, has been applied, specifically the classic grounded theory (CGT) guidelines have been used.
Search strategy keywords include those only directly descriptive of CGT.
Only publications written in English will be included for review.

Grounded theory (GT) was initially developed by Glaser and Strauss 1 as a research methodology to generate theory from data. Used extensively in the discipline of nursing since 1970, 2 GT systematically gathers and analyses data in the generation of theory. 3 Theories generated via GT methods are said to be grounded in data, meaning data drives the generation of theory instead of applying a theoretical framework to the research design, data collection and analysis. 4 GT is a universal research method that can be undertaken using three different approaches: Classic (or Glasserian), Straussian or Constructivist. 5

The aim of classic grounded theory (CGT) is to generate, develop or discover a theory, 1 and theories generated from CGT research can act as drivers of change. 4 Data collection and analysis occur simultaneously in CGT, with codes and categories developed from data through a constant comparative method that facilitates the emergence of a theory. 3 The GT method advocates line-by-line coding as a first step because it forces the researcher to take a fresh look at the data, compare data fragments and ask analytic questions about them. This method of analysis facilitates data synthesis but, more importantly, allows CGT researchers to move beyond description through forming new concepts that explicate what is happening.

The CGT approach offers valuable strategies to develop researchers’ theoretical analyses 6 and presents important opportunities to develop, enhance and improve nurse behaviours. For example, Flenady et al 7 undertook a CGT study to explain the behaviours of emergency department registered nurses (RNs) when they perform respiratory rate observations. Analysis of data collected from 79 RNs revealed that health sectors forced compliance in recording observations meant that this group of RNs are more than likely to record a respiratory rate without actually counting respirations. 7 The emergent theory called ‘Rationalising Transgression’ identified two significant factors that impact current practice. 7 First, RNs in emergency departments report suboptimal practice occurring regarding respiratory rate collection methods and second, this poor practice occurs in part because nurses believe that respiratory rate observations are not required for every patient. Second, organisational requirements mandate that a value for this vital sign be given at each observation round are superfluous and redundant. From this CGT study, valuable insight into the behaviours of this cohort of nurses was identified and and important understanding of how these observations were collected was ascertained—both important factors that impact patient safety and quality nursing practice. 7

Despite the important contribution of GT to nursing practice and knowledge, elements related to rigour are not always well understood and challenges continue to arise concerning authentication and trustworthiness when applying GT as a research methodology. 8–10 Moher 11 recommends reporting criteria as essential for researchers so that the disclosure of research methods and findings is transparent and explicit. Significant work has been undertaken in creating quality criteria and recommendations when executing qualitative research. 12 Yet, it has been suggested the domain of qualitative research is unnecessarily brimming with templates and standard protocols, and the use of such templates is considered to enhance the rigour of qualitative research. 13 It is assumed that only practices that increase methodological transparency, and thereby increase the replicability of one’s research, are essential for trustworthiness. 14 However, there is a growing school of thought that rather than using rigid templates and protocols, the use of guiding principles and researchers’ own reasoning through the application of the methodology is in itself a trustworthy template for rigour. 13

The use of GT in nursing-related studies has grown significantly over the last 20 years, and with this increasing popularity, recurrent calls for enhancing rigour and quality have been made. 12 Ambiguity regarding rigour when dealing with narratives and people rather than numbers and statistics continues, 15 therefore it is beneficial that qualitative researchers have the ability to establish that their research is credible. 8 Tobin and Begley (p. 369) 10 state ‘without rigour, there is the potential of fictional journalism masquerading as research!’

CGT was the sole focus of this systematic review because the authors’ particular interest was to appraise the methodological accuracy of CGT studies to determine if the tenets were followed when discovering a substantive theory.

Few publications exist that appraise the accurate application of GT methodology within health research. In 2009, Ali et al undertook a systematic review which appraised the methodological rigour of GT research published in the field of physiotherapy. 16 They found one of the main problems that undermined the rigour of GT studies was the multiple versions of GT methods used. This problem manifested itself in a state of methodological incoherence whereby methods seemed mixed and matched. The authors concluded, such methodological incoherence might have prevented the analysis from progressing beyond the concrete level of describing information because the abstract level of exploring, explaining and theorising variations within data was not present. 16 Similarly, Valvi et al undertook a critical evaluation of GT studies that focused on online and mobile customer behaviours. 17 Their study identified weaknesses regarding the methodological conduct of the GT which impacted the resulting generation of theory. 17 Valvi et al found that it was apparent from their critical evaluation that researchers’ had pre-conceptions and inadequate knowledge of GT methodology and concluded firm knowledge of the different versions of GT ought to precede GT application. 17

Likewise, Hutchison et al critically reviewed GT research within exercise physiology. 18 They reviewed 21 articles that report on GT studies conducted between 1999 and 2008 and concluded it was crucial that both authors and reviewers of future studies understand the key tenets of GT methodology and the limitations associated. 18 Research rigour in GT can only be judged if authors present a clear and detailed account of their research process and researchers must recognise that GT represents a complete research process where appropriate actions need to be considered at every stage. 18

The earliest process of undertaking CGT as specified by Glaser and Strauss in 1967 included constant comparison, systematic coding, theoretical sampling and writing of memos. While this iterative process was evident, there was a lack of clear guidelines for researchers to follow. In response to these identified methodological deficits, a Guideline for Reporting and Evaluating Grounded Theory (GUREGT) research studies was developed by Berthelsen et al . 19 The GUREGT is a validated, 25-item checklist that, that CGT researchers can employ when they aim to produce a study, addresses the main tenants of the GT approach. 19 Berthelsen et al concluded that when the GUREGT is used for reporting or evaluating GT studies, researchers’ ability to identify information missing in manuscripts, as well as preserve the theoretical sensitivity of GT studies is enhanced (p. 75). 19

With the increasing use and misuse of GT in nursing research, it is essential that researchers understand and identify the differences when applying the three main types of GT methodology 20 and the intention of this systematic review was to focus on one iteration of GT, CGT. The GUREGT provides a benchmark for rigour in regard to the components required to produce a high-quality theory. The GUREGT also provided us with a well-defined list of divergence between the three main iterations of GT.

CGT is a valuable methodology for informing nursing-related studies. 21 However, there is a paucity of literature evaluating the application quality of GT studies in nursing, particularly CGT. This systematic review will apply the constructs of GUREGT to appraise how consistently researchers adhere to the principles of CGT methodology. The results of this review will provide a framework to inform the precise application of CGT in future research. This in turn will enhance the rigour of subsequent CGT studies, which will better inform nursing practice and education going forward.

Review aim and objectives

This systematic review aims to develop an understanding of the application of CGT methodology in the field of nursing research. Specifically, this review will appraise the quality of its application against the validated framework, the GUREGT, explicitly the CGT guiding principles.

Eligibility criteria

Types of studies.

Studies included will be peer-reviewed journal articles that identify using a CGT methodology within the field of nursing.

Types of participants

Only research relating to nurses in the fields of acute, community, educational or general specialty areas will be considered. This does not include the wider medical or allied health professions, or the discipline of midwifery.

Patient and public involvement

There is no patient or public involvement in the design, conduct, reporting, or dissemination plans of this research.

Types of data

Applied nursing research studies that used CGT methodology and published between 2010 and 2022, in English peer-reviewed journals, will be used to generate the data for this systematic review.

Types of methods

To be included, studies must be conducted applying only CGT methodology.

Types of outcomes

The outcomes will be based on the use of CGT as the primary and only methodology used in a study related to nursing that reports a substantive GT.

Information sources

Literature search strategies will be developed using medical subject headings (MeSH) and text words related to CGT and nursing. We will search Cumulative Index of Nursing and Allied Health Literature, PubMed/MEDLINE and ProQuest—Nursing and Allied Health databases. The literature search will be limited to the English language and nursing-related studies. To ensure we capture all relevant literature, we will hand search the reference lists of retrieved results as well as search for included authors’ previous publications to ensure we achieve literature saturation. The reporting of this review will be guided by the preferred reporting items for systematic and meta-analysis guidelines statement 22 and data synthesis guided by the Synthesis Without Meta-analysis guideline. 23

Search strategy

The search strategy was developed from free text and controlled (MeSH) vocabularies. A review of the search strategy was undertaken by a senior research librarian. Testing of search results was undertaken using the following Problem, Intervention and Context (PICo) framework 24 ( table 1 ).

PICo framework 24

Study records

The results from each database search will be imported to the lead researcher’s endnote library to a folder labelled with the database, this will ensure the ongoing and future auditability of databases. There will also be a folder titled ‘hand search results’. All files will then be copied to an overarching folder to combine results. Duplicates will be removed at this stage and the remaining results will be uploaded to the collaborative screening platform, Rayyan ( https://www.rayyan.ai/ ).

Study selection

Level 1 screening will consist of two reviewers, JC and TF, who will independently assess each study’s title and abstract in Rayyan. All four reviewers, JC, TF, DM and TD, will undertake level 2 screening, reviewing the full text of each article, with discussions occurring to resolve any conflicts.

Level 1 inclusion criteria require checking titles and abstracts to ensure included studies:

State they use a CGT methodology.
Are focused on the nursing discipline.

Level 2 screening involves the researchers reading the full text of included studies to scrutinise the manuscripts for the following inclusion criteria:

CGT is applied to the overarching nursing study
CGT is not only used as a method for data collection or analysis.
CGT not embedded into other qualitative methods (case studies, comparisons) or types of studies (literature review, scoping review).
The aim of the CGT study was to develop a substantive GT.

While the authors recognise there may be limitations because they have searched for CGT in the title, it is frequently identified that publications state they are using CGT but are in fact using hybrid or mixtures of GT methodology. We believe it would be highly unlikely for the study to not mention Classic, or Glaserian, if the researcher followed CGT.

Prior to starting, data extraction guidance notes will be created by JC. A data extraction table will be developed to collect the following information from each study:

Country where the study was conducted.
Aim and/or objectives.

Guidelines for reporting and evaluating grounded theory research studies (GUREGT) tool—12 main areas 19

Outcome of systematic review

Quality appraisal of publications will be conducted using the GUREGT and critique of the methodological quality of each individual study will be undertaken by all four researchers, JC, TF, DM and TD. The primary outcome of this review will be to apply the GUREGT to appraise the extent CGT methodology and methods have been accurately applied in published nursing studies. This will be presented in a detailed visual displaying the elements of the GUREGT that are ‘evident’, ‘partially evident’ and ‘not evident’ within the data set. This will inform the discussion and results of the review.

Data extraction

Based on the GUREGT main areas and items, an Excel extraction tool was designed by JC for the extraction of data from all studies. This extraction tool was reviewed by the three other team members, and all four team members will independently extract the data, with any concerns or disagreements being resolved as a group. Using the validated GUREGT, the 12 main areas and 25 items of CGT method (see table 2 ) will be extracted, collated and appraised using an excel spreadsheet. Extracted data will be in the form of evident/partially evident/not evident to all areas and items of the GUREGT tool.

Risk of bias

The risk of bias will be minimised by assessing studies using the GUREGT guidelines and the Critical Appraisals Skills Programme (CASP) checklist for systematic reviews ( https://casp-uk.net/casp-tools-checklists/ ). JC will independently undertake CASP appraisal and share outcomes and discuss any concerns with the other three members of the research team. Critical appraisal skills enable researchers to systematically assess the trustworthiness, relevance and results of published papers.

There are four assessors in this systematic review. Three are experienced qualitative researchers and the fourth (and primary author) is a PhD candidate with some experience in qualitative approaches. Three of the four have undertaken and presented peer-reviewed GT studies with one completing their PhD using CGT methodology. All are RNs with three having in excess of 25 years each nursing experience across multiple healthcare environments.

Data synthesis

A systematic narrative synthesis will be provided with information presented in the text and tables to summarise and display the characteristics and findings of the included studies. The narrative synthesis will explore the relationship and findings both within and between the included studies, in line with the guidance from the Centre for Reviews and Dissemination. When addressing some items in the GUREGT, authors have concluded that some or all of the expected data will not be suitable for combining quantitatively. Therefore, the following seven items 2b, 4c, 6d, 8b, 8d, 9b, 9d will describe the results and outcomes in narrative form.

The data synthesis will primarily be completed by JC, with a second a full review being completed by TF, TD and DM. The results will be compared and discussed in meetings between all authors to provide feedback and resolve any outstanding concerns.

Secondary data will be attained in this systematic review therefore no ethical approval is required. Other ethical issues are unexpected. The registration record of this systematic review is with the International Prospective Register of Systematic Reviews ( https://www.crd.york.ac.uk/prospero ) Protocol Registration. The results of the final study will be published in a peer-reviewed open-access journal and academic symposiums and/or conferences. It is expected that results will inform future CGT research.

Supplementary Material

Acknowledgments.

We are grateful to KS, senior research librarian of CQ University Library for her helpful comments on the search strategy. Proof reading assistance was provided by DO, PhD with thanks.

Twitter: @JusConnor25

Contributors: JC is the guarantor of the review. JC led the development of the protocol and drafted the manuscript. JC, TF, TD and DM contributed to the development of the eligibility criteria and selection process. TF, TD and DM all read drafts of the manuscript, provided feedback and approved the final manuscript.

Funding: The primary researcher on this project is a Research Higher Degree candidate supported under the Australian Commonwealth Government’s Research Training Program/Research Training Scheme. The candidate gratefully acknowledges the financial support provided by the Australian Government.

Competing interests: None declared.

Patient and public involvement: Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Provenance and peer review: Not commissioned; externally peer reviewed.

Ethics statements

Patient consent for publication.

Not applicable.

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In the field of research, the term method represents the specific approaches and procedures that the researcher systematically utilizes that are manifested in the research design, sampling design, data collec-tion, data analysis, data interpretation, and so forth. The literature review represents a method because the literature reviewer chooses ...
Methodological Approaches to Literature Review
Qualitative systematic review/qualitative evidence synthesis: Method for integrating or comparing the findings from qualitative studies. It seeks to identify "themes" or "constructs" that lie in or across individual qualitative studies. ... The purpose, process, and methods of writing a literature review. AORN J. 2016;103(3):265-9 ...
Reviewing the research methods literature: principles and strategies
The conventional focus of rigorous literature reviews (i.e., review types for which systematic methods have been codified, including the various approaches to quantitative systematic reviews [2-4], and the numerous forms of qualitative and mixed methods literature synthesis [5-10]) is to synthesize empirical research findings from multiple ...
Qualitative Research: Literature Review
In The Literature Review: A Step-by-Step Guide for Students, Ridley presents that literature reviews serve several purposes (2008, p. 16-17). Included are the following points: Historical background for the research; Overview of current field provided by "contemporary debates, issues, and questions;" Theories and concepts related to your research;
Guidance on Conducting a Systematic Literature Review
A search on EBSCOhost using keywords "review methodology," "literature review," and "research synthesis" returned 653 records of peer-reviewed articles. After initial title screening, we found twenty-two records related to the methodology of literature review. ... They then review the qualitative literature and revise their ranked ...
Chapter 9. Reviewing the Literature
A literature review is a comprehensive summary of previous research on a topic. It includes both articles and books—and in some cases reports—relevant to a particular area of research. Ideally, one's research question follows from the reading of what has already been produced. For example, you are interested in studying sports injuries ...
PDF Qualitative Analysis Techniques for the Review of the Literature
A literature review is a written document that presents a logically argued case founded on a comprehensive understanding of the current state of knowledge about a topic of study. This case establishes a convincing thesis to answer the study's question. (p. 4) Despite this complexity, most research methodology textbooks only devote at most one ...
A Guide to Writing a Qualitative Systematic Review Protocol to ...
Methodology: The key elements required in a systematic review protocol are discussed, with a focus on application to qualitative reviews: Development of a research question; formulation of key search terms and strategies; designing a multistage review process; critical appraisal of qualitative literature; development of data extraction ...
Qualitative systematic reviews: their importance for our understanding
A qualitative systematic review brings together research on a topic, systematically searching for research evidence from primary qualitative studies and drawing the findings together. There is a debate over whether the search needs to be exhaustive. 1 , 2 Methods for systematic reviews of quantitative research are well established and explicit ...
Strategies for completing a successful integrative review
This article describes one type of literature review—an integrative review—and provides a framework and some guidelines for conducting an integrative review. ... (34 quantitative, 4 mixed method, and 1 qualitative). Data evaluation: Although this is no "gold standard" for evaluating articles included in an integrative review, ...
Literature Review: The What, Why and How-to Guide
Example: Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework: 10.1177/08948453211037398 ; Systematic review: "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139).
How to Operate Literature Review Through Qualitative and ...
Scholars have traditionally used the qualitative approach to a systematic literature review and the quantitative approach to a meta-analysis . Zupic and Cater [ 12 ] introduced a third method - science mapping - based on the quantitative approach of bibliometric research methods and is increasingly being used to map the structure and ...
What is a Literature Review?
A literature review is a review and synthesis of existing research on a topic or research question. A literature review is meant to analyze the scholarly literature, make connections across writings and identify strengths, weaknesses, trends, and missing conversations. ... including the largest collection of qualitative methods books available ...
Full article: Methodology or method? A critical review of qualitative
Study design. The critical review method described by Grant and Booth (Citation 2009) was used, which is appropriate for the assessment of research quality, and is used for literature analysis to inform research and practice.This type of review goes beyond the mapping and description of scoping or rapid reviews, to include "analysis and conceptual innovation" (Grant & Booth, Citation 2009 ...
Literature Review Research
Literature Review is a comprehensive survey of the works published in a particular field of study or line of research, usually over a specific period of time, in the form of an in-depth, critical bibliographic essay or annotated list in which attention is drawn to the most significant works. Also, we can define a literature review as the ...
Qualitative or Quantitative?
Quantitative Research (an operational definition) Quantitative research: an operational description. Purpose: explain, predict or control phenomena through focused collection and analysis of numberical data. Approach: deductive; tries to be value-free/has objectives/ is outcome-oriented. Hypotheses: Specific, testable, and stated prior to study.
Qualitative research
Through writing your literature review, you are likely to have identified either a problem that need 'fixing' or a gap that your research may begin to fill. ... The methodology is the instruction manual: the procedure and steps you have taken, using your chosen tools, to tackle the research problem. ... In qualitative studies, your results ...
Criteria for Good Qualitative Research: A Comprehensive Review
This review aims to synthesize a published set of evaluative criteria for good qualitative research. The aim is to shed light on existing standards for assessing the rigor of qualitative research encompassing a range of epistemological and ontological standpoints. Using a systematic search strategy, published journal articles that deliberate criteria for rigorous research were identified. Then ...
Writing a Literature Review
The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say "literature review" or refer to "the literature," we are talking about the research (scholarship) in a given field. You will often see the terms "the research," "the ...
(PDF) Literature review on qualitative methods and standards for
Aitken, Stuart, C. and Thomas Herma n (2009), 'Literature Review on Qualitative Methods . and Standards for Engaging an d Studying Independent Children in the Developing World',
Types of reviews
Types of reviews and examples. Definition: "A term used to describe a conventional overview of the literature, particularly when contrasted with a systematic review (Booth et al., 2012, p. 265). Characteristics: Example: Mitchell, L. E., & Zajchowski, C. A. (2022). The history of air quality in Utah: A narrative review.
Methods Section Of Literature Review Example and Format
Qualitative Methods in Literature Review Tools. For a qualitative literature review approach, semi-structured interviews were conducted with 8 returning customers of a fitness store to gain insights into potential improvements in the product range. Returning customers were defined as those who usually made purchases at least twice weekly.
Quantitative analysis of the effects of essential oil mouthrinses on
The rich diversity of microorganisms in the oral cavity plays an important role in the maintenance of oral health and development of detrimental oral health conditions. Beyond commonly used qualitative microbiome metrics, such as relative proportions or diversity, both the species-level identification and quantification of bacteria are key to understanding clinical disease associations.
Application of classic grounded theory in nursing studies: a
CGT is the only methodology applied to the study. CGT is not only used as a method for data collection or analysis. CGT not embedded into other qualitative methods (case studies, comparisons) or types of studies (literature review, scoping review). The aim of the CGT study was to develop a substantive GT.
Sustainability
Sustainable development goals challenge the carbon lock-in dilemma of the industrial economy, and identifying the motivation and mechanism behind carbon unlocking has become an urgent priority. With its inclusive and precise advantages, digital finance (DF) provides a new impetus for the economy's low-carbon transformation, while reasonable environmental regulation (ER) acts as an important ...
About Stop Overdose
Key points. Through preliminary research and strategic workshops, CDC identified four areas of focus to address the evolving drug overdose crisis. Stop Overdose resources speak to the reality of drug use, provide practical ways to prevent overdoses, educate about the risks of illegal drug use, and show ways to get help.

Archer Library

Exploring the literature review

Your Literature Review

1. Select a Topic

Consider Purpose

★ Schedule a research appointment

2. Search the Literature

Books & eBooks: Archer Library & OhioLINK

Databases: Theses & Dissertations

Newspapers: Databases & Internet

Search Strategies & Boolean Operators

Overview of boolean terms

Database Search Limiters

★ Truncating Search Terms

Asterisk (*) Wildcard

★ EBSCO Databases & Google Drive

Researching in an EBSCO database?

EBSCO Databases & Google Drive

Defining Literature Review

Recommended Reading

About this page

Archer Librarians

Archer Library • Ashland University © Copyright 2023. An Equal Opportunity/Equal Access Institution.

Chapter 9. Reviewing the Literature

Examples of Literature Reviews

Reader-Friendly Example: The Power of Peers

Authoritative Academic Journal Example: Working Class Students’ College Expectations

Embracing Theory

Helpful Tips

Where to Start Looking for Literature

Keep a List of Your Keywords

Think Laterally

Read Outside the Canon

Consider Multiple Uses for Literature

Describing Gaps in the Literature

Use Concept Mapping

Ask Yourself, “How Is This Sociology (or Political Science or Public Policy, Etc.)?”

Don’t Treat This as a Chore

Supplement: Two More Literature Review Examples

”Changing Dispositions among the Upwardly Mobile” by Curl, Lareau, and Wu ( 2018 )

Further Readings

A Guide to Writing a Qualitative Systematic Review Protocol to Enhance Evidence-Based Practice in Nursing and Health Care

Literature Review: The What, Why and How-to Guide — Introduction

What are Literature Reviews?

Goals of Literature Reviews

Types of Literature Reviews

Literature Reviews in the Health Sciences

Libraries | Research Guides

Research Methods

Literature Review

University Libraries

Literature Reviews

Qualitative researchers TEND to:

Qualitative Research (an operational definition)

Some Other Guidelines

Quantitative researchers TEND to:

Quantitative Research (an operational definition)

Dissertations and research projects

Developing a theoretical framework

Why do I need a theoretical framework?

How do I choose the 'right' approach?

Introduction

Literature review

Methodology

A summary of your key findings – what you have concluded from your research, and how far you have been able to successfully answer your research questions.

Alternative structure

Criteria for Good Qualitative Research: A Comprehensive Review

Cite this article

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Good Qualitative Research: Opening up the Debate

What is Qualitative in Research

Introduction

Criteria for Evaluating Qualitative Studies

Qualitative Research: Interpretive Paradigms

Improving Quality: Strategies

How to Assess the Quality of the Research Findings?

Quality Checklists: Tools for Assessing the Quality

Conclusions, Future Directions, and Outlook

Prospects : A Road Ahead for Qualitative Research

Author information