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Assignments

The assignments in this course are openly licensed, and are available as-is, or can be modified to suit your students’ needs. Selected answer keys are available to faculty who adopt Waymaker, OHM, or Candela courses with paid support from Lumen Learning. This approach helps us protect the academic integrity of these materials by ensuring they are shared only with authorized and institution-affiliated faculty and staff.

If you import this course into your learning management system (Blackboard, Canvas, etc.), the assignments will automatically be loaded into the assignment tool, where they may be adjusted, or edited there. Assignments also come with rubrics and pre-assigned point values that may easily be edited or removed.

The assignments for Introductory Psychology are ideas and suggestions to use as you see appropriate. Some are larger assignments spanning several weeks, while others are smaller, less-time consuming tasks. You can view them below or throughout the course.

You can view them below or throughout the course.

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How to demonstrate critical evaluation in your psychology assignments

psychology assignment examples

Thinking critically about psychology research

Critical thinking is often taught in undergraduate psychology degrees, and is a key marking criteria for higher marks in many assignments. But getting your head around how to write critically can sometimes be difficult. It can take practice. The aim of this short blog is to provide an introduction to critical evaluation, and how to start including evidence of critical evaluation in your psychology assignments.

So what does “critical evaluation” really mean?

Broadly speaking, critical evaluation is the process of thinking and writing critically about the quality of the sources of evidence used to support or refute an argument. By “ evidence “, I mean the literature you cite (e.g., a journal article or book chapter). By “ quality   of the evidence “, I mean thinking about whether this topic has been tested is in a robust way. If the quality of the sources is poor, then this could suggest poor support for your argument, and vice versa. Even if the quality is poor, this is important to discuss in your assignments as evidence of critical thinking in this way!

In the rest of this blog, I outline a few different ways you can start to implement critical thinking into your work and reading of psychology. I talk about the quality of the evidence, a few pointers for critiquing the methods, theoretical and practical critical evaluation too. This is not an exhaustive list, but hopefully it’ll help you to start getting those higher-level marks in psychology. I also include an example write-up at the end to illustrate how to write all of this up!

The quality of the evidence

There are different types of study designs in psychology research, but some are of higher quality than others. The higher the quality of the evidence, the stronger the support for your argument the research offers, because the idea has been tested more rigorously. The pyramid image below can really help to explain what we mean by “quality of evidence”, by showing different study designs in the order of their quality. 

Not every area of psychology is going to be full of high quality studies, and even the strongest sources of evidence (i.e., systematic reviews and/or meta-analyses) can have limitations! Because no study is perfect, it can be a good habit to tell the reader, in your report, (i) what the  design  of the study is that you’re citing, AND, (ii)  how  this affects your argument. Doing so would be evidence of critical thought. (See an example write-up below for implementing this, but do not copy and paste it!) 

But first, what do I mean by “design”? The design of the study refers to  how  the study was carried out. There are sometimes broad categories of design that you’ll have heard of, like a ‘survey design’, ‘a review paper’, or an ‘experimental design’. Within these categories, though, there can be more specific types of design (e.g. a  cross-sectional  survey design, or a  longitudinal  survey design; a  randomised controlled  experiment or a  simple pre-post  experiment). Knowing these specific types of design is a good place to start when thinking about how to critique the evidence when citing your sources, and the image below can help with that. 

hierarchy of scientific evidence, randomized controlled study, case, cohort, research design

Image source: https://thelogicofscience.com/2016/01/12/the-hierarchy-of-evidence-is-the-studys-design-robust/

In summary, there are various types of designs in psychology research. To name a few from the image above, we have: a meta-analysis or a systematic review (a review paper that summarises the research that explores the same research question); a cross-sectional survey study (a questionnaire that people complete once – these are really common in psychology!). If you’re not familiar with these, I would  highly suggest  doing a bit of reading around these methods and some of their general limitations – you can then use these limitation points in your assignments! To help with this, you could do a Google Scholar search for ‘limitations of a cross-sectional study’, or ‘why are randomised control trials gold standard?’. You can use any published papers as further support as a limitation.

Methodological critical evaluation

  • Internal validity: Are the findings or the measures used in the study reliable (e.g., have they been replicated by another study, and is the reliability high)? 
  • External validity: Are there any biases in the study that might affect generalisability(e.g., gender bias, where one gender may be overrepresented for the population in the sample recruited)?  Lack of generalisability is a common limitation that undergraduates tend to use by default as a limitation in their reports. It’s a perfectly valid limitation, but it can usually be made much more impactful by explaining exactly  how  it’s a problem for the topic of study. In some cases, this limitation may not be all that warranted; for example, a female bias may be expected in a sample of psychology students, because undergraduate courses tend to be filled mostly with females! 
  • What is the design of the study, and how it a good or bad quality design (randomised control trial, cross-sectional study)? 

Theoretical critical evaluation

  • Do the findings in the literature support the relevant psychological theories?
  • Have the findings been replicated in another study? (If so, say so and add a reference!)

Practical critical evaluation

  • In the real world, how easy would it be to implement these findings?
  • Have these findings been implemented? (If so, you could find out if this has been done well!)

Summary points

In summary, there are various types of designs in psychology research. To name a few from the image above, we have: a meta-analysis or a systematic review (a review paper that summarises the research that explores the same research question); a cross-sectional survey study (a questionnaire that people complete once – these are really common in psychology!). If you’re not familiar with these, I would highly suggest doing a bit of reading around these methods and some of their general limitations – you can then use these limitation points in your assignments! To help with this, I would do a Google Scholar search for ‘limitations of a cross-sectional study’, or ‘why are randomised control trials gold standard?’. You can use these papers as further support as a limitation.

You don’t have to use all of these points in your writing, these are just examples of how you can demonstrate critical thinking in your work. Try to use at least a couple in any assignment. Here is an example of how to write these up:

An example write-up

“Depression and anxiety are generally associated with each other (see the meta-analysis by [reference here]). For example, one of these studies was a cross-sectional study [reference here] with 500 undergraduate psychology students. The researchers found that depression and anxiety (measured using the DASS-21 measure) were correlated at  r  = .76, indicating a strong effect. However, this one study is limited in that it used a cross-sectional design, which do not tell us whether depression causes anxiety or whether anxiety causes depression; it just tells us that they are correlated. It’s also limited in that the participants are not a clinical sample, which does not tell us about whether these are clinically co-morbid constructs. Finally, a strength of this study is that it used the DASS-21 which is generally found to be a reliable measure. Future studies would therefore benefit from using a longitudinal design to gain an idea as to how these variables are causally related to one another, and use more clinical samples to understand the implications for clinical practice. Overall, however, the research generally suggests that depression and anxiety are associated. That there is a meta-analysis on this topic [reference here], showing that there is lots of evidence, suggests that this finding is generally well-accepted.”

  • Notice how I first found a review paper on the topic to broadly tell the reader how much evidence there is in the first place. I set the scene of the paragraph with the first sentence, and then the last sentence I brought it back, rounding the paragraph off. 
  • Notice how I then described one study from this paper in more detail. Specifically, I mentioned the participants, the design of the study and the measure the researchers used to assess these variables. Critically, I then described  how  each of these pieces of the method are disadvantages/strengths of the study. Sometimes, it’s enough to just say “the study was limited in that it was a cross-sectional study”, but it can really show that you are thinking critically, if you also add “… because it does not tell us….”. 
  • Notice how I added a statistic there to further illustrate my point (in this case, it was the correlation coefficient), showing that I didn’t just read the abstract of the paper. Doing this for the effect sizes in a study can also help demonstrate to a reader that you understand statistics (a higher-level marking criteria). 

Are these points you can include in your own work?

Thanks for reading,

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Course info.

  • Prof. Jeremy Wolfe

Departments

  • Brain and Cognitive Sciences

As Taught In

  • Cognitive Science

Learning Resource Types

Introduction to psychology, assignments, the general idea.

Over the course of the term, you need to write three different kinds of papers and revise one of them.

Each of these will be about 6 pages long (about 1800 words). The revision will be a bit longer.

On the server, there is a folder associated with each lecture and/or chapter. In the folder you will find pdfs of an article or two (sometimes a URL pointing to an article). The contents of the folder will be described on the handout for that lecture/chapter. The handouts are also on the web. Your work for each of the papers begins with one (or more) of these articles. What you do with the article(s) will depend on the kind of paper you are writing. (See below).

General Requirements: Sources

  • Each of the first three papers must use at least one of the articles posted on the server.
  • Each of the first three papers must use at least two sources beyond what is on the website.
  • Those two sources must be published in the scholarly literature or in book form (College level textbooks are fine for one of the two sources. No…you can’t use Gleitman.)
  • If you are in doubt about the scholarly nature of a source, ask your TA or ask the librarians (good reason to go to a library workshop).
  • A random webpage found by ‘Googling’ cannot be counted toward the two scholarly resources; BUT it might be useful. You can use such sources. You can cite them (give the URL). You just can’t rely on them exclusively.
  • Electronic versions of scholarly publications (like most of what I have put on the server) are just fine.
  • When in doubt, ASK.

General Requirements: Writing

Always, always make sure you are using your own words. Direct quotation can be used but only very sparingly. It is rarely needed in this sort of writing. Direct quotes should be “in quotes” of course and a proper citation should be given. What we really want to avoid are papers where you read a paragraph and then write a paragraph that is a close paraphrase of your source. Changing “I discovered” to “She discovered” is not “using your own words”. Read your sources. Take notes on your sources. Think about the material. Then write something of your own. If your paper is a pastiche of near quotes, we are going to give you a really bad grade. You have been warned.

Citation: We are not particularly concerned about the form of citation that you use. I suggest following the model used in Gleitman. You put an author and year marker in the text at the relevant point (Wolfe, 2004) and a suitable bibliographic reference at the end of the paper.

Wolfe, J. M. “Writing Assignments for Intro.” Psych. Journal of Course Requirements 12, no. 4 (2004): 403-405.

The critical requirement is that we should be able to find the source of any facts and ideas that you gleaned in your reading. Again, when in doubt, ask.

The Four Papers

Paper 1: Writing for the Public ( PDF )

Paper 2: Taking the Next Step ( PDF )

Examples of Good and Bad Writing ( PDF )

Paper 3: Rewriting the Textbook ( PDF )

Paper 4: Revision ( PDF )

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Resources: Discussions and Assignments

Assignment: foundations of psychology, topics in psychology.

STEP 1 : Visit the TED Talks website and search for a talk on the subject matter of psychology. Watch one of the talks that interests you, as long as it is a minimum of 8 minutes in length. At the top of your response, include the title of the TED Talk, the name of the presenter, when it was filmed, along with a link to the video.

STEP 2 : In an essay of between 200-400 words, respond to the following:

  • Give a summary of the TED talk, emphasizing the speaker’s main points
  • What did you find most interesting about the talk, and what will you most likely remember from the talk?
  • What type of data or evidence did the presenter show to back up their information?
  • Read the biographical information and do some basic background research on the presenter. What area of psychology do they work in? More specifically, which psychological perspective would you say best fits the type of work they do? Why?
  • What other questions would you have for this presenter if you could have a conversation with them? What else would you like to know about the topic?
  • Ted Talk Perspectives Assignment. Provided by : Lumen Learning. License : CC BY: Attribution

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The Writing Center • University of North Carolina at Chapel Hill

What this handout is about

This handout discusses some of the common writing assignments in psychology courses, and it presents strategies for completing them. The handout also provides general tips for writing psychology papers and for reducing bias in your writing.

What is psychology?

Psychology, one of the behavioral sciences, is the scientific study of observable behaviors, like sleeping, and abstract mental processes, such as dreaming. Psychologists study, explain, and predict behaviors. Because of the complexity of human behaviors, researchers use a variety of methods and approaches.  They ask questions about behaviors and answer them using systematic methods. For example, to understand why female students tend to perform better in school than their male classmates, psychologists have examined whether parents, teachers, schools, and society behave in ways that support the educational outcomes of female students to a greater extent than those of males.

Writing in psychology

Writing in psychology is similar to other forms of scientific writing in that organization, clarity, and concision are important.  The Psychology Department at UNC has a strong research emphasis, so many of your assignments will focus on synthesizing and critically evaluating research, connecting your course material with current research literature, and designing and carrying out your own studies.

Common assignments

Reaction papers.

These assignments ask you to react to a scholarly journal article.  Instructors use reaction papers to teach students to critically evaluate research and to synthesize current research with course material.  Reaction papers typically include a brief summary of the article, including prior research, hypotheses, research method, main results, and conclusions. The next step is your critical reaction. You might critique the study, identify unresolved issues, suggest future research, or reflect on the study’s implications.  Some instructors may want you to connect the material you are learning in class with the article’s theories, methodology, and findings. Remember, reaction papers require more than a simple summary of what you have read.

To successfully complete this assignment, you should carefully read the article. Go beyond highlighting important facts and interesting findings. Ask yourself questions as you read: What are the researchers’ assumptions? How does the article contribute to the field? Are the findings generalizable, and to whom?  Are the conclusions valid and based on the results?  It is important to pay attention to the graphs and tables because they can help you better assess the researchers’ claims.

Your instructor may give you a list of articles to choose from, or you may need to find your own.  The American Psychological Association (APA) PsycINFO database is the most comprehensive collection of psychology research; it is an excellent resource for finding journal articles.  You can access PsycINFO from the E-research tab on the Library’s webpage.   Here are the most common types of articles you will find:

  • Empirical studies test hypotheses by gathering and analyzing data. Empirical articles are organized into distinct sections based on stages in the research process: introduction, method, results, and discussion.
  • Literature reviews synthesize previously published material on a topic.  The authors define or clarify the problem, summarize research findings, identify gaps/inconsistencies in the research, and make suggestions for future work. Meta-analyses, in which the authors use quantitative procedures to combine the results of multiple studies, fall into this category.
  • Theoretical articles trace the development of a specific theory to expand or refine it, or they present a new theory.  Theoretical articles and literature reviews are organized similarly, but empirical information is included in theoretical articles only when it is used to support the theoretical issue.

You may also find methodological articles, case studies, brief reports, and commentary on previously published material. Check with your instructor to determine which articles are appropriate.

Research papers

This assignment involves using published research to provide an overview of and argument about a topic.  Simply summarizing the information you read is not enough. Instead, carefully synthesize the information to support your argument. Only discuss the parts of the studies that are relevant to your argument or topic.  Headings and subheadings can help guide readers through a long research paper. Our handout on literature reviews may help you organize your research literature.

Choose a topic that is appropriate to the length of the assignment and for which you can find adequate sources. For example, “self-esteem” might be too broad for a 10- page paper, but it may be difficult to find enough articles on “the effects of private school education on female African American children’s self-esteem.” A paper in which you focus on the more general topic of “the effects of school transitions on adolescents’ self-esteem,” however, might work well for the assignment.

Designing your own study/research proposal

You may have the opportunity to design and conduct your own research study or write about the design for one in the form of a research proposal. A good approach is to model your paper on articles you’ve read for class. Here is a general overview of the information that should be included in each section of a research study or proposal:

  • Introduction: The introduction conveys a clear understanding of what will be done and why. Present the problem, address its significance, and describe your research strategy. Also discuss the theories that guide the research, previous research that has been conducted, and how your study builds on this literature. Set forth the hypotheses and objectives of the study.
  • Methods:   This section describes the procedures used to answer your research questions and provides an overview of the analyses that you conducted. For a research proposal, address the procedures that will be used to collect and analyze your data. Do not use the passive voice in this section. For example, it is better to say, “We randomly assigned patients to a treatment group and monitored their progress,” instead of “Patients were randomly assigned to a treatment group and their progress was monitored.” It is acceptable to use “I” or “we,” instead of the third person, when describing your procedures. See the section on reducing bias in language for more tips on writing this section and for discussing the study’s participants.
  • Results: This section presents the findings that answer your research questions. Include all data, even if they do not support your hypotheses.  If you are presenting statistical results, your instructor will probably expect you to follow the style recommendations of the American Psychological Association. You can also consult our handout on figures and charts . Note that research proposals will not include a results section, but your instructor might expect you to hypothesize about expected results.
  • Discussion: Use this section to address the limitations of your study as well as the practical and/or theoretical implications of the results. You should contextualize and support your conclusions by noting how your results compare to the work of others. You can also discuss questions that emerged and call for future research. A research proposal will not include a discussion section.  But you can include a short section that addresses the proposed study’s contribution to the literature on the topic.

Other writing assignments

For some assignments, you may be asked to engage personally with the course material. For example, you might provide personal examples to evaluate a theory in a reflection paper.  It is appropriate to share personal experiences for this assignment, but be mindful of your audience and provide only relevant and appropriate details.

Writing tips for psychology papers

Psychology is a behavioral science, and writing in psychology is similar to writing in the hard sciences.  See our handout on writing in the sciences .  The Publication Manual of the American Psychological Association provides an extensive discussion on how to write for the discipline.  The Manual also gives the rules for psychology’s citation style, called APA. The Library’s citation tutorial will also introduce you to the APA style.

Suggestions for achieving precision and clarity in your writing

  • Jargon: Technical vocabulary that is not essential to understanding your ideas can confuse readers. Similarly, refrain from using euphemistic phrases instead of clearer terms.  Use “handicapped” instead of “handi-capable,” and “poverty” instead of “monetarily felt scarcity,” for example.
  • Anthropomorphism: Anthropomorphism occurs when human characteristics are attributed to animals or inanimate entities.  Anthropomorphism can make your writing awkward.  Some examples include: “The experiment attempted to demonstrate…,” and “The tables compare…”  Reword such sentences so that a person performs the action: “The experimenter attempted to demonstrate…”  The verbs “show” or “indicate” can also be used: “The tables show…”
  • Verb tenses: Select verb tenses carefully. Use the past tense when expressing actions or conditions that occurred at a specific time in the past, when discussing other people’s work, and when reporting results.  Use the present perfect tense to express past actions or conditions that did not occur at a specific time, or to describe an action beginning in the past and continuing in the present.
  • Pronoun agreement: Be consistent within and across sentences with pronouns that refer to a noun introduced earlier (antecedent). A common error is a construction such as “Each child responded to questions about their favorite toys.” The sentence should have either a plural subject (children) or a singular pronoun (his or her). Vague pronouns, such as “this” or “that,” without a clear antecedent can confuse readers: “This shows that girls are more likely than boys …” could be rewritten as “These results show that girls are more likely than boys…”
  • Avoid figurative language and superlatives: Scientific writing should be as concise and specific as possible.  Emotional language and superlatives, such as “very,” “highly,” “astonishingly,” “extremely,” “quite,” and even “exactly,” are imprecise or unnecessary. A line that is “exactly 100 centimeters” is, simply, 100 centimeters.
  • Avoid colloquial expressions and informal language: Use “children” rather than “kids;” “many” rather than “a lot;” “acquire” rather than “get;” “prepare for” rather than “get ready;” etc.

Reducing bias in language

Your writing should show respect for research participants and readers, so it is important to choose language that is clear, accurate, and unbiased.  The APA sets forth guidelines for reducing bias in language: acknowledge participation, describe individuals at the appropriate level of specificity, and be sensitive to labels. Here are some specific examples of how to reduce bias in your language:

  • Acknowledge participation: Use the active voice to acknowledge the subjects’ participation. It is preferable to say, “The students completed the surveys,” instead of “The experimenters administered surveys to the students.”  This is especially important when writing about participants in the methods section of a research study.
  • Gender: It is inaccurate to use the term “men” when referring to groups composed of multiple genders. See our handout on gender-inclusive language for tips on writing appropriately about gender.
  • Race/ethnicity: Be specific, consistent, and sensitive with terms for racial and ethnic groups. If the study participants are Chinese Americans, for instance, don’t refer to them as Asian Americans. Some ethnic designations are outdated or have negative connotations. Use terms that the individuals or groups prefer.
  • Clinical terms: Broad clinical terms can be unclear. For example, if you mention “at risk” in your paper, be sure to specify the risk—“at risk for school failure.”  The same principle applies to psychological disorders. For instance, “borderline personality disorder” is more precise than “borderline.”
  • Labels: Do not equate people with their physical or mental conditions or categorize people broadly as objects. For example, adjectival forms like “older adults” are preferable to labels such as “the elderly” or “the schizophrenics.” Another option is to mention the person first, followed by a descriptive phrase— “people diagnosed with schizophrenia.”  Be careful using the label “normal,” as it may imply that others are abnormal.
  • Other ways to reduce bias: Consistently presenting information about the socially dominant group first can promote bias. Make sure that you don’t always begin with men followed by other genders when writing about gender, or whites followed by minorities when discussing race and ethnicity. Mention differences only when they are relevant and necessary to understanding the study. For example, it may not be important to indicate the sexual orientation of participants in a study about a drug treatment program’s effectiveness. Sexual orientation may be important to mention, however, when studying bullying among high school students.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

American Psychological Association. n.d. “Frequently Asked Questions About APA Style®.” APA Style. Accessed June 24, 2019. https://apastyle.apa.org/learn/faqs/index .

American Psychological Association. 2010. Publication Manual of the American Psychological Association . 6th ed. Washington, DC: American Psychological Association.

Landrum, Eric. 2008. Undergraduate Writing in Psychology: Learning to Tell the Scientific Story . Washington, DC: American Psychological Association.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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Random Assignment in Psychology: Definition & Examples

Julia Simkus

Editor at Simply Psychology

BA (Hons) Psychology, Princeton University

Julia Simkus is a graduate of Princeton University with a Bachelor of Arts in Psychology. She is currently studying for a Master's Degree in Counseling for Mental Health and Wellness in September 2023. Julia's research has been published in peer reviewed journals.

Learn about our Editorial Process

Saul Mcleod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

In psychology, random assignment refers to the practice of allocating participants to different experimental groups in a study in a completely unbiased way, ensuring each participant has an equal chance of being assigned to any group.

In experimental research, random assignment, or random placement, organizes participants from your sample into different groups using randomization. 

Random assignment uses chance procedures to ensure that each participant has an equal opportunity of being assigned to either a control or experimental group.

The control group does not receive the treatment in question, whereas the experimental group does receive the treatment.

When using random assignment, neither the researcher nor the participant can choose the group to which the participant is assigned. This ensures that any differences between and within the groups are not systematic at the onset of the study. 

In a study to test the success of a weight-loss program, investigators randomly assigned a pool of participants to one of two groups.

Group A participants participated in the weight-loss program for 10 weeks and took a class where they learned about the benefits of healthy eating and exercise.

Group B participants read a 200-page book that explains the benefits of weight loss. The investigator randomly assigned participants to one of the two groups.

The researchers found that those who participated in the program and took the class were more likely to lose weight than those in the other group that received only the book.

Importance 

Random assignment ensures that each group in the experiment is identical before applying the independent variable.

In experiments , researchers will manipulate an independent variable to assess its effect on a dependent variable, while controlling for other variables. Random assignment increases the likelihood that the treatment groups are the same at the onset of a study.

Thus, any changes that result from the independent variable can be assumed to be a result of the treatment of interest. This is particularly important for eliminating sources of bias and strengthening the internal validity of an experiment.

Random assignment is the best method for inferring a causal relationship between a treatment and an outcome.

Random Selection vs. Random Assignment 

Random selection (also called probability sampling or random sampling) is a way of randomly selecting members of a population to be included in your study.

On the other hand, random assignment is a way of sorting the sample participants into control and treatment groups. 

Random selection ensures that everyone in the population has an equal chance of being selected for the study. Once the pool of participants has been chosen, experimenters use random assignment to assign participants into groups. 

Random assignment is only used in between-subjects experimental designs, while random selection can be used in a variety of study designs.

Random Assignment vs Random Sampling

Random sampling refers to selecting participants from a population so that each individual has an equal chance of being chosen. This method enhances the representativeness of the sample.

Random assignment, on the other hand, is used in experimental designs once participants are selected. It involves allocating these participants to different experimental groups or conditions randomly.

This helps ensure that any differences in results across groups are due to manipulating the independent variable, not preexisting differences among participants.

When to Use Random Assignment

Random assignment is used in experiments with a between-groups or independent measures design.

In these research designs, researchers will manipulate an independent variable to assess its effect on a dependent variable, while controlling for other variables.

There is usually a control group and one or more experimental groups. Random assignment helps ensure that the groups are comparable at the onset of the study.

How to Use Random Assignment

There are a variety of ways to assign participants into study groups randomly. Here are a handful of popular methods: 

  • Random Number Generator : Give each member of the sample a unique number; use a computer program to randomly generate a number from the list for each group.
  • Lottery : Give each member of the sample a unique number. Place all numbers in a hat or bucket and draw numbers at random for each group.
  • Flipping a Coin : Flip a coin for each participant to decide if they will be in the control group or experimental group (this method can only be used when you have just two groups) 
  • Roll a Die : For each number on the list, roll a dice to decide which of the groups they will be in. For example, assume that rolling 1, 2, or 3 places them in a control group and rolling 3, 4, 5 lands them in an experimental group.

When is Random Assignment not used?

  • When it is not ethically permissible: Randomization is only ethical if the researcher has no evidence that one treatment is superior to the other or that one treatment might have harmful side effects. 
  • When answering non-causal questions : If the researcher is just interested in predicting the probability of an event, the causal relationship between the variables is not important and observational designs would be more suitable than random assignment. 
  • When studying the effect of variables that cannot be manipulated: Some risk factors cannot be manipulated and so it would not make any sense to study them in a randomized trial. For example, we cannot randomly assign participants into categories based on age, gender, or genetic factors.

Drawbacks of Random Assignment

While randomization assures an unbiased assignment of participants to groups, it does not guarantee the equality of these groups. There could still be extraneous variables that differ between groups or group differences that arise from chance. Additionally, there is still an element of luck with random assignments.

Thus, researchers can not produce perfectly equal groups for each specific study. Differences between the treatment group and control group might still exist, and the results of a randomized trial may sometimes be wrong, but this is absolutely okay.

Scientific evidence is a long and continuous process, and the groups will tend to be equal in the long run when data is aggregated in a meta-analysis.

Additionally, external validity (i.e., the extent to which the researcher can use the results of the study to generalize to the larger population) is compromised with random assignment.

Random assignment is challenging to implement outside of controlled laboratory conditions and might not represent what would happen in the real world at the population level. 

Random assignment can also be more costly than simple observational studies, where an investigator is just observing events without intervening with the population.

Randomization also can be time-consuming and challenging, especially when participants refuse to receive the assigned treatment or do not adhere to recommendations. 

What is the difference between random sampling and random assignment?

Random sampling refers to randomly selecting a sample of participants from a population. Random assignment refers to randomly assigning participants to treatment groups from the selected sample.

Does random assignment increase internal validity?

Yes, random assignment ensures that there are no systematic differences between the participants in each group, enhancing the study’s internal validity .

Does random assignment reduce sampling error?

Yes, with random assignment, participants have an equal chance of being assigned to either a control group or an experimental group, resulting in a sample that is, in theory, representative of the population.

Random assignment does not completely eliminate sampling error because a sample only approximates the population from which it is drawn. However, random sampling is a way to minimize sampling errors. 

When is random assignment not possible?

Random assignment is not possible when the experimenters cannot control the treatment or independent variable.

For example, if you want to compare how men and women perform on a test, you cannot randomly assign subjects to these groups.

Participants are not randomly assigned to different groups in this study, but instead assigned based on their characteristics.

Does random assignment eliminate confounding variables?

Yes, random assignment eliminates the influence of any confounding variables on the treatment because it distributes them at random among the study groups. Randomization invalidates any relationship between a confounding variable and the treatment.

Why is random assignment of participants to treatment conditions in an experiment used?

Random assignment is used to ensure that all groups are comparable at the start of a study. This allows researchers to conclude that the outcomes of the study can be attributed to the intervention at hand and to rule out alternative explanations for study results.

Further Reading

  • Bogomolnaia, A., & Moulin, H. (2001). A new solution to the random assignment problem .  Journal of Economic theory ,  100 (2), 295-328.
  • Krause, M. S., & Howard, K. I. (2003). What random assignment does and does not do .  Journal of Clinical Psychology ,  59 (7), 751-766.

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An assignment examples on psychology s is a prosaic composition of a small volume and free composition, expressing individual impressions and thoughts on a specific occasion or issue and obviously not claiming a definitive or exhaustive interpretation of the subject.

Some signs of psychology s assignment:

  • the presence of a specific topic or question. A work devoted to the analysis of a wide range of problems in biology, by definition, cannot be performed in the genre of psychology s assignment topic.
  • The assignment expresses individual impressions and thoughts on a specific occasion or issue, in this case, on psychology s and does not knowingly pretend to a definitive or exhaustive interpretation of the subject.
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The goal of an assignment in psychology s is to develop such skills as independent creative thinking and writing out your own thoughts.

Writing an assignment is extremely useful, because it allows the author to learn to clearly and correctly formulate thoughts, structure information, use basic concepts, highlight causal relationships, illustrate experience with relevant examples, and substantiate his conclusions.

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What Is a Case Study?

Weighing the pros and cons of this method of research

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

psychology assignment examples

Cara Lustik is a fact-checker and copywriter.

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  • Pros and Cons

What Types of Case Studies Are Out There?

Where do you find data for a case study, how do i write a psychology case study.

A case study is an in-depth study of one person, group, or event. In a case study, nearly every aspect of the subject's life and history is analyzed to seek patterns and causes of behavior. Case studies can be used in many different fields, including psychology, medicine, education, anthropology, political science, and social work.

The point of a case study is to learn as much as possible about an individual or group so that the information can be generalized to many others. Unfortunately, case studies tend to be highly subjective, and it is sometimes difficult to generalize results to a larger population.

While case studies focus on a single individual or group, they follow a format similar to other types of psychology writing. If you are writing a case study, we got you—here are some rules of APA format to reference.  

At a Glance

A case study, or an in-depth study of a person, group, or event, can be a useful research tool when used wisely. In many cases, case studies are best used in situations where it would be difficult or impossible for you to conduct an experiment. They are helpful for looking at unique situations and allow researchers to gather a lot of˜ information about a specific individual or group of people. However, it's important to be cautious of any bias we draw from them as they are highly subjective.

What Are the Benefits and Limitations of Case Studies?

A case study can have its strengths and weaknesses. Researchers must consider these pros and cons before deciding if this type of study is appropriate for their needs.

One of the greatest advantages of a case study is that it allows researchers to investigate things that are often difficult or impossible to replicate in a lab. Some other benefits of a case study:

  • Allows researchers to capture information on the 'how,' 'what,' and 'why,' of something that's implemented
  • Gives researchers the chance to collect information on why one strategy might be chosen over another
  • Permits researchers to develop hypotheses that can be explored in experimental research

On the other hand, a case study can have some drawbacks:

  • It cannot necessarily be generalized to the larger population
  • Cannot demonstrate cause and effect
  • It may not be scientifically rigorous
  • It can lead to bias

Researchers may choose to perform a case study if they want to explore a unique or recently discovered phenomenon. Through their insights, researchers develop additional ideas and study questions that might be explored in future studies.

It's important to remember that the insights from case studies cannot be used to determine cause-and-effect relationships between variables. However, case studies may be used to develop hypotheses that can then be addressed in experimental research.

Case Study Examples

There have been a number of notable case studies in the history of psychology. Much of  Freud's work and theories were developed through individual case studies. Some great examples of case studies in psychology include:

  • Anna O : Anna O. was a pseudonym of a woman named Bertha Pappenheim, a patient of a physician named Josef Breuer. While she was never a patient of Freud's, Freud and Breuer discussed her case extensively. The woman was experiencing symptoms of a condition that was then known as hysteria and found that talking about her problems helped relieve her symptoms. Her case played an important part in the development of talk therapy as an approach to mental health treatment.
  • Phineas Gage : Phineas Gage was a railroad employee who experienced a terrible accident in which an explosion sent a metal rod through his skull, damaging important portions of his brain. Gage recovered from his accident but was left with serious changes in both personality and behavior.
  • Genie : Genie was a young girl subjected to horrific abuse and isolation. The case study of Genie allowed researchers to study whether language learning was possible, even after missing critical periods for language development. Her case also served as an example of how scientific research may interfere with treatment and lead to further abuse of vulnerable individuals.

Such cases demonstrate how case research can be used to study things that researchers could not replicate in experimental settings. In Genie's case, her horrific abuse denied her the opportunity to learn a language at critical points in her development.

This is clearly not something researchers could ethically replicate, but conducting a case study on Genie allowed researchers to study phenomena that are otherwise impossible to reproduce.

There are a few different types of case studies that psychologists and other researchers might use:

  • Collective case studies : These involve studying a group of individuals. Researchers might study a group of people in a certain setting or look at an entire community. For example, psychologists might explore how access to resources in a community has affected the collective mental well-being of those who live there.
  • Descriptive case studies : These involve starting with a descriptive theory. The subjects are then observed, and the information gathered is compared to the pre-existing theory.
  • Explanatory case studies : These   are often used to do causal investigations. In other words, researchers are interested in looking at factors that may have caused certain things to occur.
  • Exploratory case studies : These are sometimes used as a prelude to further, more in-depth research. This allows researchers to gather more information before developing their research questions and hypotheses .
  • Instrumental case studies : These occur when the individual or group allows researchers to understand more than what is initially obvious to observers.
  • Intrinsic case studies : This type of case study is when the researcher has a personal interest in the case. Jean Piaget's observations of his own children are good examples of how an intrinsic case study can contribute to the development of a psychological theory.

The three main case study types often used are intrinsic, instrumental, and collective. Intrinsic case studies are useful for learning about unique cases. Instrumental case studies help look at an individual to learn more about a broader issue. A collective case study can be useful for looking at several cases simultaneously.

The type of case study that psychology researchers use depends on the unique characteristics of the situation and the case itself.

There are a number of different sources and methods that researchers can use to gather information about an individual or group. Six major sources that have been identified by researchers are:

  • Archival records : Census records, survey records, and name lists are examples of archival records.
  • Direct observation : This strategy involves observing the subject, often in a natural setting . While an individual observer is sometimes used, it is more common to utilize a group of observers.
  • Documents : Letters, newspaper articles, administrative records, etc., are the types of documents often used as sources.
  • Interviews : Interviews are one of the most important methods for gathering information in case studies. An interview can involve structured survey questions or more open-ended questions.
  • Participant observation : When the researcher serves as a participant in events and observes the actions and outcomes, it is called participant observation.
  • Physical artifacts : Tools, objects, instruments, and other artifacts are often observed during a direct observation of the subject.

If you have been directed to write a case study for a psychology course, be sure to check with your instructor for any specific guidelines you need to follow. If you are writing your case study for a professional publication, check with the publisher for their specific guidelines for submitting a case study.

Here is a general outline of what should be included in a case study.

Section 1: A Case History

This section will have the following structure and content:

Background information : The first section of your paper will present your client's background. Include factors such as age, gender, work, health status, family mental health history, family and social relationships, drug and alcohol history, life difficulties, goals, and coping skills and weaknesses.

Description of the presenting problem : In the next section of your case study, you will describe the problem or symptoms that the client presented with.

Describe any physical, emotional, or sensory symptoms reported by the client. Thoughts, feelings, and perceptions related to the symptoms should also be noted. Any screening or diagnostic assessments that are used should also be described in detail and all scores reported.

Your diagnosis : Provide your diagnosis and give the appropriate Diagnostic and Statistical Manual code. Explain how you reached your diagnosis, how the client's symptoms fit the diagnostic criteria for the disorder(s), or any possible difficulties in reaching a diagnosis.

Section 2: Treatment Plan

This portion of the paper will address the chosen treatment for the condition. This might also include the theoretical basis for the chosen treatment or any other evidence that might exist to support why this approach was chosen.

  • Cognitive behavioral approach : Explain how a cognitive behavioral therapist would approach treatment. Offer background information on cognitive behavioral therapy and describe the treatment sessions, client response, and outcome of this type of treatment. Make note of any difficulties or successes encountered by your client during treatment.
  • Humanistic approach : Describe a humanistic approach that could be used to treat your client, such as client-centered therapy . Provide information on the type of treatment you chose, the client's reaction to the treatment, and the end result of this approach. Explain why the treatment was successful or unsuccessful.
  • Psychoanalytic approach : Describe how a psychoanalytic therapist would view the client's problem. Provide some background on the psychoanalytic approach and cite relevant references. Explain how psychoanalytic therapy would be used to treat the client, how the client would respond to therapy, and the effectiveness of this treatment approach.
  • Pharmacological approach : If treatment primarily involves the use of medications, explain which medications were used and why. Provide background on the effectiveness of these medications and how monotherapy may compare with an approach that combines medications with therapy or other treatments.

This section of a case study should also include information about the treatment goals, process, and outcomes.

When you are writing a case study, you should also include a section where you discuss the case study itself, including the strengths and limitiations of the study. You should note how the findings of your case study might support previous research. 

In your discussion section, you should also describe some of the implications of your case study. What ideas or findings might require further exploration? How might researchers go about exploring some of these questions in additional studies?

Need More Tips?

Here are a few additional pointers to keep in mind when formatting your case study:

  • Never refer to the subject of your case study as "the client." Instead, use their name or a pseudonym.
  • Read examples of case studies to gain an idea about the style and format.
  • Remember to use APA format when citing references .

Crowe S, Cresswell K, Robertson A, Huby G, Avery A, Sheikh A. The case study approach .  BMC Med Res Methodol . 2011;11:100.

Crowe S, Cresswell K, Robertson A, Huby G, Avery A, Sheikh A. The case study approach . BMC Med Res Methodol . 2011 Jun 27;11:100. doi:10.1186/1471-2288-11-100

Gagnon, Yves-Chantal.  The Case Study as Research Method: A Practical Handbook . Canada, Chicago Review Press Incorporated DBA Independent Pub Group, 2010.

Yin, Robert K. Case Study Research and Applications: Design and Methods . United States, SAGE Publications, 2017.

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Random Assignment in Psychology (Definition + 40 Examples)

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Have you ever wondered how researchers discover new ways to help people learn, make decisions, or overcome challenges? A hidden hero in this adventure of discovery is a method called random assignment, a cornerstone in psychological research that helps scientists uncover the truths about the human mind and behavior.

Random Assignment is a process used in research where each participant has an equal chance of being placed in any group within the study. This technique is essential in experiments as it helps to eliminate biases, ensuring that the different groups being compared are similar in all important aspects.

By doing so, researchers can be confident that any differences observed are likely due to the variable being tested, rather than other factors.

In this article, we’ll explore the intriguing world of random assignment, diving into its history, principles, real-world examples, and the impact it has had on the field of psychology.

History of Random Assignment

two women in different conditions

Stepping back in time, we delve into the origins of random assignment, which finds its roots in the early 20th century.

The pioneering mind behind this innovative technique was Sir Ronald A. Fisher , a British statistician and biologist. Fisher introduced the concept of random assignment in the 1920s, aiming to improve the quality and reliability of experimental research .

His contributions laid the groundwork for the method's evolution and its widespread adoption in various fields, particularly in psychology.

Fisher’s groundbreaking work on random assignment was motivated by his desire to control for confounding variables – those pesky factors that could muddy the waters of research findings.

By assigning participants to different groups purely by chance, he realized that the influence of these confounding variables could be minimized, paving the way for more accurate and trustworthy results.

Early Studies Utilizing Random Assignment

Following Fisher's initial development, random assignment started to gain traction in the research community. Early studies adopting this methodology focused on a variety of topics, from agriculture (which was Fisher’s primary field of interest) to medicine and psychology.

The approach allowed researchers to draw stronger conclusions from their experiments, bolstering the development of new theories and practices.

One notable early study utilizing random assignment was conducted in the field of educational psychology. Researchers were keen to understand the impact of different teaching methods on student outcomes.

By randomly assigning students to various instructional approaches, they were able to isolate the effects of the teaching methods, leading to valuable insights and recommendations for educators.

Evolution of the Methodology

As the decades rolled on, random assignment continued to evolve and adapt to the changing landscape of research.

Advances in technology introduced new tools and techniques for implementing randomization, such as computerized random number generators, which offered greater precision and ease of use.

The application of random assignment expanded beyond the confines of the laboratory, finding its way into field studies and large-scale surveys.

Researchers across diverse disciplines embraced the methodology, recognizing its potential to enhance the validity of their findings and contribute to the advancement of knowledge.

From its humble beginnings in the early 20th century to its widespread use today, random assignment has proven to be a cornerstone of scientific inquiry.

Its development and evolution have played a pivotal role in shaping the landscape of psychological research, driving discoveries that have improved lives and deepened our understanding of the human experience.

Principles of Random Assignment

Delving into the heart of random assignment, we uncover the theories and principles that form its foundation.

The method is steeped in the basics of probability theory and statistical inference, ensuring that each participant has an equal chance of being placed in any group, thus fostering fair and unbiased results.

Basic Principles of Random Assignment

Understanding the core principles of random assignment is key to grasping its significance in research. There are three principles: equal probability of selection, reduction of bias, and ensuring representativeness.

The first principle, equal probability of selection , ensures that every participant has an identical chance of being assigned to any group in the study. This randomness is crucial as it mitigates the risk of bias and establishes a level playing field.

The second principle focuses on the reduction of bias . Random assignment acts as a safeguard, ensuring that the groups being compared are alike in all essential aspects before the experiment begins.

This similarity between groups allows researchers to attribute any differences observed in the outcomes directly to the independent variable being studied.

Lastly, ensuring representativeness is a vital principle. When participants are assigned randomly, the resulting groups are more likely to be representative of the larger population.

This characteristic is crucial for the generalizability of the study’s findings, allowing researchers to apply their insights broadly.

Theoretical Foundation

The theoretical foundation of random assignment lies in probability theory and statistical inference .

Probability theory deals with the likelihood of different outcomes, providing a mathematical framework for analyzing random phenomena. In the context of random assignment, it helps in ensuring that each participant has an equal chance of being placed in any group.

Statistical inference, on the other hand, allows researchers to draw conclusions about a population based on a sample of data drawn from that population. It is the mechanism through which the results of a study can be generalized to a broader context.

Random assignment enhances the reliability of statistical inferences by reducing biases and ensuring that the sample is representative.

Differentiating Random Assignment from Random Selection

It’s essential to distinguish between random assignment and random selection, as the two terms, while related, have distinct meanings in the realm of research.

Random assignment refers to how participants are placed into different groups in an experiment, aiming to control for confounding variables and help determine causes.

In contrast, random selection pertains to how individuals are chosen to participate in a study. This method is used to ensure that the sample of participants is representative of the larger population, which is vital for the external validity of the research.

While both methods are rooted in randomness and probability, they serve different purposes in the research process.

Understanding the theories, principles, and distinctions of random assignment illuminates its pivotal role in psychological research.

This method, anchored in probability theory and statistical inference, serves as a beacon of reliability, guiding researchers in their quest for knowledge and ensuring that their findings stand the test of validity and applicability.

Methodology of Random Assignment

woman sleeping with a brain monitor

Implementing random assignment in a study is a meticulous process that involves several crucial steps.

The initial step is participant selection, where individuals are chosen to partake in the study. This stage is critical to ensure that the pool of participants is diverse and representative of the population the study aims to generalize to.

Once the pool of participants has been established, the actual assignment process begins. In this step, each participant is allocated randomly to one of the groups in the study.

Researchers use various tools, such as random number generators or computerized methods, to ensure that this assignment is genuinely random and free from biases.

Monitoring and adjusting form the final step in the implementation of random assignment. Researchers need to continuously observe the groups to ensure that they remain comparable in all essential aspects throughout the study.

If any significant discrepancies arise, adjustments might be necessary to maintain the study’s integrity and validity.

Tools and Techniques Used

The evolution of technology has introduced a variety of tools and techniques to facilitate random assignment.

Random number generators, both manual and computerized, are commonly used to assign participants to different groups. These generators ensure that each individual has an equal chance of being placed in any group, upholding the principle of equal probability of selection.

In addition to random number generators, researchers often use specialized computer software designed for statistical analysis and experimental design.

These software programs offer advanced features that allow for precise and efficient random assignment, minimizing the risk of human error and enhancing the study’s reliability.

Ethical Considerations

The implementation of random assignment is not devoid of ethical considerations. Informed consent is a fundamental ethical principle that researchers must uphold.

Informed consent means that every participant should be fully informed about the nature of the study, the procedures involved, and any potential risks or benefits, ensuring that they voluntarily agree to participate.

Beyond informed consent, researchers must conduct a thorough risk and benefit analysis. The potential benefits of the study should outweigh any risks or harms to the participants.

Safeguarding the well-being of participants is paramount, and any study employing random assignment must adhere to established ethical guidelines and standards.

Conclusion of Methodology

The methodology of random assignment, while seemingly straightforward, is a multifaceted process that demands precision, fairness, and ethical integrity. From participant selection to assignment and monitoring, each step is crucial to ensure the validity of the study’s findings.

The tools and techniques employed, coupled with a steadfast commitment to ethical principles, underscore the significance of random assignment as a cornerstone of robust psychological research.

Benefits of Random Assignment in Psychological Research

The impact and importance of random assignment in psychological research cannot be overstated. It is fundamental for ensuring the study is accurate, allowing the researchers to determine if their study actually caused the results they saw, and making sure the findings can be applied to the real world.

Facilitating Causal Inferences

When participants are randomly assigned to different groups, researchers can be more confident that the observed effects are due to the independent variable being changed, and not other factors.

This ability to determine the cause is called causal inference .

This confidence allows for the drawing of causal relationships, which are foundational for theory development and application in psychology.

Ensuring Internal Validity

One of the foremost impacts of random assignment is its ability to enhance the internal validity of an experiment.

Internal validity refers to the extent to which a researcher can assert that changes in the dependent variable are solely due to manipulations of the independent variable , and not due to confounding variables.

By ensuring that each participant has an equal chance of being in any condition of the experiment, random assignment helps control for participant characteristics that could otherwise complicate the results.

Enhancing Generalizability

Beyond internal validity, random assignment also plays a crucial role in enhancing the generalizability of research findings.

When done correctly, it ensures that the sample groups are representative of the larger population, so can allow researchers to apply their findings more broadly.

This representative nature is essential for the practical application of research, impacting policy, interventions, and psychological therapies.

Limitations of Random Assignment

Potential for implementation issues.

While the principles of random assignment are robust, the method can face implementation issues.

One of the most common problems is logistical constraints. Some studies, due to their nature or the specific population being studied, find it challenging to implement random assignment effectively.

For instance, in educational settings, logistical issues such as class schedules and school policies might stop the random allocation of students to different teaching methods .

Ethical Dilemmas

Random assignment, while methodologically sound, can also present ethical dilemmas.

In some cases, withholding a potentially beneficial treatment from one of the groups of participants can raise serious ethical questions, especially in medical or clinical research where participants' well-being might be directly affected.

Researchers must navigate these ethical waters carefully, balancing the pursuit of knowledge with the well-being of participants.

Generalizability Concerns

Even when implemented correctly, random assignment does not always guarantee generalizable results.

The types of people in the participant pool, the specific context of the study, and the nature of the variables being studied can all influence the extent to which the findings can be applied to the broader population.

Researchers must be cautious in making broad generalizations from studies, even those employing strict random assignment.

Practical and Real-World Limitations

In the real world, many variables cannot be manipulated for ethical or practical reasons, limiting the applicability of random assignment.

For instance, researchers cannot randomly assign individuals to different levels of intelligence, socioeconomic status, or cultural backgrounds.

This limitation necessitates the use of other research designs, such as correlational or observational studies , when exploring relationships involving such variables.

Response to Critiques

In response to these critiques, people in favor of random assignment argue that the method, despite its limitations, remains one of the most reliable ways to establish cause and effect in experimental research.

They acknowledge the challenges and ethical considerations but emphasize the rigorous frameworks in place to address them.

The ongoing discussion around the limitations and critiques of random assignment contributes to the evolution of the method, making sure it is continuously relevant and applicable in psychological research.

While random assignment is a powerful tool in experimental research, it is not without its critiques and limitations. Implementation issues, ethical dilemmas, generalizability concerns, and real-world limitations can pose significant challenges.

However, the continued discourse and refinement around these issues underline the method's enduring significance in the pursuit of knowledge in psychology.

By being careful with how we do things and doing what's right, random assignment stays a really important part of studying how people act and think.

Real-World Applications and Examples

man on a treadmill

Random assignment has been employed in many studies across various fields of psychology, leading to significant discoveries and advancements.

Here are some real-world applications and examples illustrating the diversity and impact of this method:

  • Medicine and Health Psychology: Randomized Controlled Trials (RCTs) are the gold standard in medical research. In these studies, participants are randomly assigned to either the treatment or control group to test the efficacy of new medications or interventions.
  • Educational Psychology: Studies in this field have used random assignment to explore the effects of different teaching methods, classroom environments, and educational technologies on student learning and outcomes.
  • Cognitive Psychology: Researchers have employed random assignment to investigate various aspects of human cognition, including memory, attention, and problem-solving, leading to a deeper understanding of how the mind works.
  • Social Psychology: Random assignment has been instrumental in studying social phenomena, such as conformity, aggression, and prosocial behavior, shedding light on the intricate dynamics of human interaction.

Let's get into some specific examples. You'll need to know one term though, and that is "control group." A control group is a set of participants in a study who do not receive the treatment or intervention being tested , serving as a baseline to compare with the group that does, in order to assess the effectiveness of the treatment.

  • Smoking Cessation Study: Researchers used random assignment to put participants into two groups. One group received a new anti-smoking program, while the other did not. This helped determine if the program was effective in helping people quit smoking.
  • Math Tutoring Program: A study on students used random assignment to place them into two groups. One group received additional math tutoring, while the other continued with regular classes, to see if the extra help improved their grades.
  • Exercise and Mental Health: Adults were randomly assigned to either an exercise group or a control group to study the impact of physical activity on mental health and mood.
  • Diet and Weight Loss: A study randomly assigned participants to different diet plans to compare their effectiveness in promoting weight loss and improving health markers.
  • Sleep and Learning: Researchers randomly assigned students to either a sleep extension group or a regular sleep group to study the impact of sleep on learning and memory.
  • Classroom Seating Arrangement: Teachers used random assignment to place students in different seating arrangements to examine the effect on focus and academic performance.
  • Music and Productivity: Employees were randomly assigned to listen to music or work in silence to investigate the effect of music on workplace productivity.
  • Medication for ADHD: Children with ADHD were randomly assigned to receive either medication, behavioral therapy, or a placebo to compare treatment effectiveness.
  • Mindfulness Meditation for Stress: Adults were randomly assigned to a mindfulness meditation group or a waitlist control group to study the impact on stress levels.
  • Video Games and Aggression: A study randomly assigned participants to play either violent or non-violent video games and then measured their aggression levels.
  • Online Learning Platforms: Students were randomly assigned to use different online learning platforms to evaluate their effectiveness in enhancing learning outcomes.
  • Hand Sanitizers in Schools: Schools were randomly assigned to use hand sanitizers or not to study the impact on student illness and absenteeism.
  • Caffeine and Alertness: Participants were randomly assigned to consume caffeinated or decaffeinated beverages to measure the effects on alertness and cognitive performance.
  • Green Spaces and Well-being: Neighborhoods were randomly assigned to receive green space interventions to study the impact on residents’ well-being and community connections.
  • Pet Therapy for Hospital Patients: Patients were randomly assigned to receive pet therapy or standard care to assess the impact on recovery and mood.
  • Yoga for Chronic Pain: Individuals with chronic pain were randomly assigned to a yoga intervention group or a control group to study the effect on pain levels and quality of life.
  • Flu Vaccines Effectiveness: Different groups of people were randomly assigned to receive either the flu vaccine or a placebo to determine the vaccine’s effectiveness.
  • Reading Strategies for Dyslexia: Children with dyslexia were randomly assigned to different reading intervention strategies to compare their effectiveness.
  • Physical Environment and Creativity: Participants were randomly assigned to different room setups to study the impact of physical environment on creative thinking.
  • Laughter Therapy for Depression: Individuals with depression were randomly assigned to laughter therapy sessions or control groups to assess the impact on mood.
  • Financial Incentives for Exercise: Participants were randomly assigned to receive financial incentives for exercising to study the impact on physical activity levels.
  • Art Therapy for Anxiety: Individuals with anxiety were randomly assigned to art therapy sessions or a waitlist control group to measure the effect on anxiety levels.
  • Natural Light in Offices: Employees were randomly assigned to workspaces with natural or artificial light to study the impact on productivity and job satisfaction.
  • School Start Times and Academic Performance: Schools were randomly assigned different start times to study the effect on student academic performance and well-being.
  • Horticulture Therapy for Seniors: Older adults were randomly assigned to participate in horticulture therapy or traditional activities to study the impact on cognitive function and life satisfaction.
  • Hydration and Cognitive Function: Participants were randomly assigned to different hydration levels to measure the impact on cognitive function and alertness.
  • Intergenerational Programs: Seniors and young people were randomly assigned to intergenerational programs to study the effects on well-being and cross-generational understanding.
  • Therapeutic Horseback Riding for Autism: Children with autism were randomly assigned to therapeutic horseback riding or traditional therapy to study the impact on social communication skills.
  • Active Commuting and Health: Employees were randomly assigned to active commuting (cycling, walking) or passive commuting to study the effect on physical health.
  • Mindful Eating for Weight Management: Individuals were randomly assigned to mindful eating workshops or control groups to study the impact on weight management and eating habits.
  • Noise Levels and Learning: Students were randomly assigned to classrooms with different noise levels to study the effect on learning and concentration.
  • Bilingual Education Methods: Schools were randomly assigned different bilingual education methods to compare their effectiveness in language acquisition.
  • Outdoor Play and Child Development: Children were randomly assigned to different amounts of outdoor playtime to study the impact on physical and cognitive development.
  • Social Media Detox: Participants were randomly assigned to a social media detox or regular usage to study the impact on mental health and well-being.
  • Therapeutic Writing for Trauma Survivors: Individuals who experienced trauma were randomly assigned to therapeutic writing sessions or control groups to study the impact on psychological well-being.
  • Mentoring Programs for At-risk Youth: At-risk youth were randomly assigned to mentoring programs or control groups to assess the impact on academic achievement and behavior.
  • Dance Therapy for Parkinson’s Disease: Individuals with Parkinson’s disease were randomly assigned to dance therapy or traditional exercise to study the effect on motor function and quality of life.
  • Aquaponics in Schools: Schools were randomly assigned to implement aquaponics programs to study the impact on student engagement and environmental awareness.
  • Virtual Reality for Phobia Treatment: Individuals with phobias were randomly assigned to virtual reality exposure therapy or traditional therapy to compare effectiveness.
  • Gardening and Mental Health: Participants were randomly assigned to engage in gardening or other leisure activities to study the impact on mental health and stress reduction.

Each of these studies exemplifies how random assignment is utilized in various fields and settings, shedding light on the multitude of ways it can be applied to glean valuable insights and knowledge.

Real-world Impact of Random Assignment

old lady gardening

Random assignment is like a key tool in the world of learning about people's minds and behaviors. It’s super important and helps in many different areas of our everyday lives. It helps make better rules, creates new ways to help people, and is used in lots of different fields.

Health and Medicine

In health and medicine, random assignment has helped doctors and scientists make lots of discoveries. It’s a big part of tests that help create new medicines and treatments.

By putting people into different groups by chance, scientists can really see if a medicine works.

This has led to new ways to help people with all sorts of health problems, like diabetes, heart disease, and mental health issues like depression and anxiety.

Schools and education have also learned a lot from random assignment. Researchers have used it to look at different ways of teaching, what kind of classrooms are best, and how technology can help learning.

This knowledge has helped make better school rules, develop what we learn in school, and find the best ways to teach students of all ages and backgrounds.

Workplace and Organizational Behavior

Random assignment helps us understand how people act at work and what makes a workplace good or bad.

Studies have looked at different kinds of workplaces, how bosses should act, and how teams should be put together. This has helped companies make better rules and create places to work that are helpful and make people happy.

Environmental and Social Changes

Random assignment is also used to see how changes in the community and environment affect people. Studies have looked at community projects, changes to the environment, and social programs to see how they help or hurt people’s well-being.

This has led to better community projects, efforts to protect the environment, and programs to help people in society.

Technology and Human Interaction

In our world where technology is always changing, studies with random assignment help us see how tech like social media, virtual reality, and online stuff affect how we act and feel.

This has helped make better and safer technology and rules about using it so that everyone can benefit.

The effects of random assignment go far and wide, way beyond just a science lab. It helps us understand lots of different things, leads to new and improved ways to do things, and really makes a difference in the world around us.

From making healthcare and schools better to creating positive changes in communities and the environment, the real-world impact of random assignment shows just how important it is in helping us learn and make the world a better place.

So, what have we learned? Random assignment is like a super tool in learning about how people think and act. It's like a detective helping us find clues and solve mysteries in many parts of our lives.

From creating new medicines to helping kids learn better in school, and from making workplaces happier to protecting the environment, it’s got a big job!

This method isn’t just something scientists use in labs; it reaches out and touches our everyday lives. It helps make positive changes and teaches us valuable lessons.

Whether we are talking about technology, health, education, or the environment, random assignment is there, working behind the scenes, making things better and safer for all of us.

In the end, the simple act of putting people into groups by chance helps us make big discoveries and improvements. It’s like throwing a small stone into a pond and watching the ripples spread out far and wide.

Thanks to random assignment, we are always learning, growing, and finding new ways to make our world a happier and healthier place for everyone!

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Explore Psychology

What Is Random Assignment in Psychology?

Categories Research Methods

What Is Random Assignment in Psychology?

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Random assignment means that every participant has the same chance of being chosen for the experimental or control group. It involves using procedures that rely on chance to assign participants to groups. Doing this means that every participant in a study has an equal opportunity to be assigned to any group.

For example, in a psychology experiment, participants might be assigned to either a control or experimental group. Some experiments might only have one experimental group, while others may have several treatment variations.

Using random assignment means that each participant has the same chance of being assigned to any of these groups.

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How to Use Random Assignment

So what type of procedures might psychologists utilize for random assignment? Strategies can include:

  • Flipping a coin
  • Assigning random numbers
  • Rolling dice
  • Drawing names out of a hat

How Does Random Assignment Work?

A psychology experiment aims to determine if changes in one variable lead to changes in another variable. Researchers will first begin by coming up with a hypothesis. Once researchers have an idea of what they think they might find in a population, they will come up with an experimental design and then recruit participants for their study.

Once they have a pool of participants representative of the population they are interested in looking at, they will randomly assign the participants to their groups.

  • Control group : Some participants will end up in the control group, which serves as a baseline and does not receive the independent variables.
  • Experimental group : Other participants will end up in the experimental groups that receive some form of the independent variables.

By using random assignment, the researchers make it more likely that the groups are equal at the start of the experiment. Since the groups are the same on other variables, it can be assumed that any changes that occur are the result of varying the independent variables.

After a treatment has been administered, the researchers will then collect data in order to determine if the independent variable had any impact on the dependent variable.

Random Assignment vs. Random Selection

It is important to remember that random assignment is not the same thing as random selection , also known as random sampling.

Random selection instead involves how people are chosen to be in a study. Using random selection, every member of a population stands an equal chance of being chosen for a study or experiment.

So random sampling affects how participants are chosen for a study, while random assignment affects how participants are then assigned to groups.

Examples of Random Assignment

Imagine that a psychology researcher is conducting an experiment to determine if getting adequate sleep the night before an exam results in better test scores.

Forming a Hypothesis

They hypothesize that participants who get 8 hours of sleep will do better on a math exam than participants who only get 4 hours of sleep.

Obtaining Participants

The researcher starts by obtaining a pool of participants. They find 100 participants from a local university. Half of the participants are female, and half are male.

Randomly Assign Participants to Groups

The researcher then assigns random numbers to each participant and uses a random number generator to randomly assign each number to either the 4-hour or 8-hour sleep groups.

Conduct the Experiment

Those in the 8-hour sleep group agree to sleep for 8 hours that night, while those in the 4-hour group agree to wake up after only 4 hours. The following day, all of the participants meet in a classroom.

Collect and Analyze Data

Everyone takes the same math test. The test scores are then compared to see if the amount of sleep the night before had any impact on test scores.

Why Is Random Assignment Important in Psychology Research?

Random assignment is important in psychology research because it helps improve a study’s internal validity. This means that the researchers are sure that the study demonstrates a cause-and-effect relationship between an independent and dependent variable.

Random assignment improves the internal validity by minimizing the risk that there are systematic differences in the participants who are in each group.

Key Points to Remember About Random Assignment

  • Random assignment in psychology involves each participant having an equal chance of being chosen for any of the groups, including the control and experimental groups.
  • It helps control for potential confounding variables, reducing the likelihood of pre-existing differences between groups.
  • This method enhances the internal validity of experiments, allowing researchers to draw more reliable conclusions about cause-and-effect relationships.
  • Random assignment is crucial for creating comparable groups and increasing the scientific rigor of psychological studies.
  • Study Guides
  • Homework Questions

Assignment 5

COMMENTS

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  16. Random Assignment in Psychology: Definition & Examples

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  18. Assignments

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    Stepping back in time, we delve into the origins of random assignment, which finds its roots in the early 20th century. The pioneering mind behind this innovative technique was Sir Ronald A. Fisher, a British statistician and biologist.Fisher introduced the concept of random assignment in the 1920s, aiming to improve the quality and reliability of experimental research.

  22. What Is Random Assignment in Psychology?

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  23. Assignment 5 (docx)

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