single case research meaning

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Educational Research Basics by Del Siegle

Single subject research.

“ Single subject research (also known as single case experiments) is popular in the fields of special education and counseling. This research design is useful when the researcher is attempting to change the behavior of an individual or a small group of individuals and wishes to document that change. Unlike true experiments where the researcher randomly assigns participants to a control and treatment group, in single subject research the participant serves as both the control and treatment group. The researcher uses line graphs to show the effects of a particular intervention or treatment.  An important factor of single subject research is that only one variable is changed at a time. Single subject research designs are “weak when it comes to external validity….Studies involving single-subject designs that show a particular treatment to be effective in changing behavior must rely on replication–across individuals rather than groups–if such results are be found worthy of generalization” (Fraenkel & Wallen, 2006, p. 318).

Suppose a researcher wished to investigate the effect of praise on reducing disruptive behavior over many days. First she would need to establish a baseline of how frequently the disruptions occurred. She would measure how many disruptions occurred each day for several days. In the example below, the target student was disruptive seven times on the first day, six times on the second day, and seven times on the third day. Note how the sequence of time is depicted on the x-axis (horizontal axis) and the dependent variable (outcome variable) is depicted on the y-axis (vertical axis).

Once a baseline of behavior has been established (when a consistent pattern emerges with at least three data points), the intervention begins. The researcher continues to plot the frequency of behavior while implementing the intervention of praise.

In this example, we can see that the frequency of disruptions decreased once praise began. The design in this example is known as an A-B design. The baseline period is referred to as A and the intervention period is identified as B.

Another design is the A-B-A design. An A-B-A design (also known as a reversal design) involves discontinuing the intervention and returning to a nontreatment condition.

Sometimes an individual’s behavior is so severe that the researcher cannot wait to establish a baseline and must begin with an intervention. In this case, a B-A-B design is used. The intervention is implemented immediately (before establishing a baseline). This is followed by a measurement without the intervention and then a repeat of the intervention.

Multiple-Baseline Design

Sometimes, a researcher may be interested in addressing several issues for one student or a single issue for several students. In this case, a multiple-baseline design is used.

“In a multiple baseline across subjects design, the researcher introduces the intervention to different persons at different times. The significance of this is that if a behavior changes only after the intervention is presented, and this behavior change is seen successively in each subject’s data, the effects can more likely be credited to the intervention itself as opposed to other variables. Multiple-baseline designs do not require the intervention to be withdrawn. Instead, each subject’s own data are compared between intervention and nonintervention behaviors, resulting in each subject acting as his or her own control (Kazdin, 1982). An added benefit of this design, and all single-case designs, is the immediacy of the data. Instead of waiting until postintervention to take measures on the behavior, single-case research prescribes continuous data collection and visual monitoring of that data displayed graphically, allowing for immediate instructional decision-making. Students, therefore, do not linger in an intervention that is not working for them, making the graphic display of single-case research combined with differentiated instruction responsive to the needs of students.” (Geisler, Hessler, Gardner, & Lovelace, 2009)

Regardless of the research design, the line graphs used to illustrate the data contain a set of common elements.

Generally, in single subject research we count the number of times something occurs in a given time period and see if it occurs more or less often in that time period after implementing an intervention. For example, we might measure how many baskets someone makes while shooting for 2 minutes. We would repeat that at least three times to get our baseline. Next, we would test some intervention. We might play music while shooting, give encouragement while shooting, or video the person while shooting to see if our intervention influenced the number of shots made. After the 3 baseline measurements (3 sets of 2 minute shooting), we would measure several more times (sets of 2 minute shooting) after the intervention and plot the time points (number of baskets made in 2 minutes for each of the measured time points). This works well for behaviors that are distinct and can be counted.

Sometimes behaviors come and go over time (such as being off task in a classroom or not listening during a coaching session). The way we can record these is to select a period of time (say 5 minutes) and mark down every 10 seconds whether our participant is on task. We make a minimum of three sets of 5 minute observations for a baseline, implement an intervention, and then make more sets of 5 minute observations with the intervention in place. We use this method rather than counting how many times someone is off task because one could continually be off task and that would only be a count of 1 since the person was continually off task. Someone who might be off task twice for 15 second would be off task twice for a score of 2. However, the second person is certainly not off task twice as much as the first person. Therefore, recording whether the person is off task at 10-second intervals gives a more accurate picture. The person continually off task would have a score of 30 (off task at every second interval for 5 minutes) and the person off task twice for a short time would have a score of 2 (off task only during 2 of the 10 second interval measures.

I also have additional information about how to record single-subject research data .

I hope this helps you better understand single subject research.

I have created a PowerPoint on Single Subject Research , which also available below as a video.

I have also created instructions for creating single-subject research design graphs with Excel .

Fraenkel, J. R., & Wallen, N. E. (2006). How to design and evaluate research in education (6th ed.). Boston, MA: McGraw Hill.

Geisler, J. L., Hessler, T., Gardner, R., III, & Lovelace, T. S. (2009). Differentiated writing interventions for high-achieving urban African American elementary students. Journal of Advanced Academics, 20, 214–247.

Del Siegle, Ph.D. University of Connecticut [email protected] www.delsiegle.info

Revised 02/02/2024

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10.1 Overview of Single-Subject Research

Learning objectives.

• Explain what single-subject research is, including how it differs from other types of psychological research.
• Explain what case studies are, including some of their strengths and weaknesses.
• Explain who uses single-subject research and why.

What Is Single-Subject Research?

Single-subject research is a type of quantitative research that involves studying in detail the behavior of each of a small number of participants. Note that the term single-subject does not mean that only one participant is studied; it is more typical for there to be somewhere between two and 10 participants. (This is why single-subject research designs are sometimes called small- n designs, where n is the statistical symbol for the sample size.) Single-subject research can be contrasted with group research , which typically involves studying large numbers of participants and examining their behavior primarily in terms of group means, standard deviations, and so on. The majority of this book is devoted to understanding group research, which is the most common approach in psychology. But single-subject research is an important alternative, and it is the primary approach in some areas of psychology.

Before continuing, it is important to distinguish single-subject research from two other approaches, both of which involve studying in detail a small number of participants. One is qualitative research, which focuses on understanding people’s subjective experience by collecting relatively unstructured data (e.g., detailed interviews) and analyzing those data using narrative rather than quantitative techniques. Single-subject research, in contrast, focuses on understanding objective behavior through experimental manipulation and control, collecting highly structured data, and analyzing those data quantitatively.

It is also important to distinguish single-subject research from case studies. A case study is a detailed description of an individual, which can include both qualitative and quantitative analyses. (Case studies that include only qualitative analyses can be considered a type of qualitative research.) The history of psychology is filled with influential cases studies, such as Sigmund Freud’s description of “Anna O.” (see Note 10.5 “The Case of “Anna O.”” ) and John Watson and Rosalie Rayner’s description of Little Albert (Watson & Rayner, 1920), who learned to fear a white rat—along with other furry objects—when the researchers made a loud noise while he was playing with the rat. Case studies can be useful for suggesting new research questions and for illustrating general principles. They can also help researchers understand rare phenomena, such as the effects of damage to a specific part of the human brain. As a general rule, however, case studies cannot substitute for carefully designed group or single-subject research studies. One reason is that case studies usually do not allow researchers to determine whether specific events are causally related, or even related at all. For example, if a patient is described in a case study as having been sexually abused as a child and then as having developed an eating disorder as a teenager, there is no way to determine whether these two events had anything to do with each other. A second reason is that an individual case can always be unusual in some way and therefore be unrepresentative of people more generally. Thus case studies have serious problems with both internal and external validity.

The Case of “Anna O.”

Sigmund Freud used the case of a young woman he called “Anna O.” to illustrate many principles of his theory of psychoanalysis (Freud, 1961). (Her real name was Bertha Pappenheim, and she was an early feminist who went on to make important contributions to the field of social work.) Anna had come to Freud’s colleague Josef Breuer around 1880 with a variety of odd physical and psychological symptoms. One of them was that for several weeks she was unable to drink any fluids. According to Freud,

She would take up the glass of water that she longed for, but as soon as it touched her lips she would push it away like someone suffering from hydrophobia.…She lived only on fruit, such as melons, etc., so as to lessen her tormenting thirst (p. 9).

But according to Freud, a breakthrough came one day while Anna was under hypnosis.

[S]he grumbled about her English “lady-companion,” whom she did not care for, and went on to describe, with every sign of disgust, how she had once gone into this lady’s room and how her little dog—horrid creature!—had drunk out of a glass there. The patient had said nothing, as she had wanted to be polite. After giving further energetic expression to the anger she had held back, she asked for something to drink, drank a large quantity of water without any difficulty, and awoke from her hypnosis with the glass at her lips; and thereupon the disturbance vanished, never to return.

Freud’s interpretation was that Anna had repressed the memory of this incident along with the emotion that it triggered and that this was what had caused her inability to drink. Furthermore, her recollection of the incident, along with her expression of the emotion she had repressed, caused the symptom to go away.

As an illustration of Freud’s theory, the case study of Anna O. is quite effective. As evidence for the theory, however, it is essentially worthless. The description provides no way of knowing whether Anna had really repressed the memory of the dog drinking from the glass, whether this repression had caused her inability to drink, or whether recalling this “trauma” relieved the symptom. It is also unclear from this case study how typical or atypical Anna’s experience was.

Figure 10.2

“Anna O.” was the subject of a famous case study used by Freud to illustrate the principles of psychoanalysis.

Wikimedia Commons – public domain.

Assumptions of Single-Subject Research

Again, single-subject research involves studying a small number of participants and focusing intensively on the behavior of each one. But why take this approach instead of the group approach? There are several important assumptions underlying single-subject research, and it will help to consider them now.

First and foremost is the assumption that it is important to focus intensively on the behavior of individual participants. One reason for this is that group research can hide individual differences and generate results that do not represent the behavior of any individual. For example, a treatment that has a positive effect for half the people exposed to it but a negative effect for the other half would, on average, appear to have no effect at all. Single-subject research, however, would likely reveal these individual differences. A second reason to focus intensively on individuals is that sometimes it is the behavior of a particular individual that is primarily of interest. A school psychologist, for example, might be interested in changing the behavior of a particular disruptive student. Although previous published research (both single-subject and group research) is likely to provide some guidance on how to do this, conducting a study on this student would be more direct and probably more effective.

A second assumption of single-subject research is that it is important to discover causal relationships through the manipulation of an independent variable, the careful measurement of a dependent variable, and the control of extraneous variables. For this reason, single-subject research is often considered a type of experimental research with good internal validity. Recall, for example, that Hall and his colleagues measured their dependent variable (studying) many times—first under a no-treatment control condition, then under a treatment condition (positive teacher attention), and then again under the control condition. Because there was a clear increase in studying when the treatment was introduced, a decrease when it was removed, and an increase when it was reintroduced, there is little doubt that the treatment was the cause of the improvement.

A third assumption of single-subject research is that it is important to study strong and consistent effects that have biological or social importance. Applied researchers, in particular, are interested in treatments that have substantial effects on important behaviors and that can be implemented reliably in the real-world contexts in which they occur. This is sometimes referred to as social validity (Wolf, 1976). The study by Hall and his colleagues, for example, had good social validity because it showed strong and consistent effects of positive teacher attention on a behavior that is of obvious importance to teachers, parents, and students. Furthermore, the teachers found the treatment easy to implement, even in their often chaotic elementary school classrooms.

Who Uses Single-Subject Research?

Single-subject research has been around as long as the field of psychology itself. In the late 1800s, one of psychology’s founders, Wilhelm Wundt, studied sensation and consciousness by focusing intensively on each of a small number of research participants. Herman Ebbinghaus’s research on memory and Ivan Pavlov’s research on classical conditioning are other early examples, both of which are still described in almost every introductory psychology textbook.

In the middle of the 20th century, B. F. Skinner clarified many of the assumptions underlying single-subject research and refined many of its techniques (Skinner, 1938). He and other researchers then used it to describe how rewards, punishments, and other external factors affect behavior over time. This work was carried out primarily using nonhuman subjects—mostly rats and pigeons. This approach, which Skinner called the experimental analysis of behavior —remains an important subfield of psychology and continues to rely almost exclusively on single-subject research. For excellent examples of this work, look at any issue of the Journal of the Experimental Analysis of Behavior . By the 1960s, many researchers were interested in using this approach to conduct applied research primarily with humans—a subfield now called applied behavior analysis (Baer, Wolf, & Risley, 1968). Applied behavior analysis plays an especially important role in contemporary research on developmental disabilities, education, organizational behavior, and health, among many other areas. Excellent examples of this work (including the study by Hall and his colleagues) can be found in the Journal of Applied Behavior Analysis .

Although most contemporary single-subject research is conducted from the behavioral perspective, it can in principle be used to address questions framed in terms of any theoretical perspective. For example, a studying technique based on cognitive principles of learning and memory could be evaluated by testing it on individual high school students using the single-subject approach. The single-subject approach can also be used by clinicians who take any theoretical perspective—behavioral, cognitive, psychodynamic, or humanistic—to study processes of therapeutic change with individual clients and to document their clients’ improvement (Kazdin, 1982).

Key Takeaways

• Single-subject research—which involves testing a small number of participants and focusing intensively on the behavior of each individual—is an important alternative to group research in psychology.
• Single-subject studies must be distinguished from case studies, in which an individual case is described in detail. Case studies can be useful for generating new research questions, for studying rare phenomena, and for illustrating general principles. However, they cannot substitute for carefully controlled experimental or correlational studies because they are low in internal and external validity.
• Single-subject research has been around since the beginning of the field of psychology. Today it is most strongly associated with the behavioral theoretical perspective, but it can in principle be used to study behavior from any perspective.
• Practice: Find and read a published article in psychology that reports new single-subject research. (A good source of articles published in the Journal of Applied Behavior Analysis can be found at http://seab.envmed.rochester.edu/jaba/jabaMostPop-2011.html .) Write a short summary of the study.

Practice: Find and read a published case study in psychology. (Use case study as a key term in a PsycINFO search.) Then do the following:

• Describe one problem related to internal validity.
• Describe one problem related to external validity.
• Generate one hypothesis suggested by the case study that might be interesting to test in a systematic single-subject or group study.

Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). Some current dimensions of applied behavior analysis. Journal of Applied Behavior Analysis , 1 , 91–97.

Freud, S. (1961). Five lectures on psycho-analysis . New York, NY: Norton.

Kazdin, A. E. (1982). Single-case research designs: Methods for clinical and applied settings . New York, NY: Oxford University Press.

Skinner, B. F. (1938). The behavior of organisms: An experimental analysis . New York, NY: Appleton-Century-Crofts.

Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology , 3 , 1–14.

Wolf, M. (1976). Social validity: The case for subjective measurement or how applied behavior analysis is finding its heart. Journal of Applied Behavior Analysis, 11 , 203–214.

Research Methods in Psychology Copyright © 2016 by University of Minnesota is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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• Perspective
• Published: 22 November 2022

Single case studies are a powerful tool for developing, testing and extending theories

• Lyndsey Nickels   ORCID: orcid.org/0000-0002-0311-3524 1 , 2 ,
• Simon Fischer-Baum   ORCID: orcid.org/0000-0002-6067-0538 3 &
• Wendy Best   ORCID: orcid.org/0000-0001-8375-5916 4  

Nature Reviews Psychology volume  1 ,  pages 733–747 ( 2022 ) Cite this article

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Psychology embraces a diverse range of methodologies. However, most rely on averaging group data to draw conclusions. In this Perspective, we argue that single case methodology is a valuable tool for developing and extending psychological theories. We stress the importance of single case and case series research, drawing on classic and contemporary cases in which cognitive and perceptual deficits provide insights into typical cognitive processes in domains such as memory, delusions, reading and face perception. We unpack the key features of single case methodology, describe its strengths, its value in adjudicating between theories, and outline its benefits for a better understanding of deficits and hence more appropriate interventions. The unique insights that single case studies have provided illustrate the value of in-depth investigation within an individual. Single case methodology has an important place in the psychologist’s toolkit and it should be valued as a primary research tool.

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The authors thank all of those pioneers of and advocates for single case study research who have mentored, inspired and encouraged us over the years, and the many other colleagues with whom we have discussed these issues.

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Nickels, L., Fischer-Baum, S. & Best, W. Single case studies are a powerful tool for developing, testing and extending theories. Nat Rev Psychol 1 , 733–747 (2022). https://doi.org/10.1038/s44159-022-00127-y

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In This Article Expand or collapse the "in this article" section Single-Case Experimental Designs

Introduction, general overviews and primary textbooks.

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• Model Building and Randomization in Single-Case Experimental Designs
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• Reporting Single-Case Design Intervention Research

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Single-Case Experimental Designs by S. Andrew Garbacz , Thomas R. Kratochwill LAST REVIEWED: 29 July 2020 LAST MODIFIED: 29 July 2020 DOI: 10.1093/obo/9780199828340-0265

Single-case experimental designs are a family of experimental designs that are characterized by researcher manipulation of an independent variable and repeated measurement of a dependent variable before (i.e., baseline) and after (i.e., intervention phase) introducing the independent variable. In single-case experimental designs a case is the unit of intervention and analysis (e.g., a child, a school). Because measurement within each case is conducted before and after manipulation of the independent variable, the case typically serves as its own control. Experimental variants of single-case designs provide a basis for determining a causal relation by replication of the intervention through (a) introducing and withdrawing the independent variable, (b) manipulating the independent variable across different phases, and (c) introducing the independent variable in a staggered fashion across different points in time. Due to their economy of resources, single-case designs may be useful during development activities and allow for rapid replication across studies.

Several sources provide overviews of single-case experimental designs. Barlow, et al. 2009 includes an overview for the development of single-case experimental designs, describes key considerations for designing and conducting single-case experimental design research, and reviews procedural elements, assessment strategies, and replication considerations. Kazdin 2011 provides detailed coverage of single-case experimental design variants as well as approaches for evaluating data in single-case experimental designs. Kratochwill and Levin 2014 describes key methodological features that underlie single-case experimental designs, including philosophical and statistical foundations and data evaluation. Ledford and Gast 2018 covers research conceptualization and writing, design variants within single-case experimental design, definitions of variables and associated measurement, and approaches to organize and evaluate data. Riley-Tillman and Burns 2009 provides a practical orientation to single-case experimental designs to facilitate uptake and use in applied settings.

Barlow, D. H., M. K. Nock, and M. Hersen, eds. 2009. Single case experimental designs: Strategies for studying behavior change . 3d ed. New York: Pearson.

A comprehensive reference about the process of designing and conducting single-case experimental design studies. Chapters are integrative but can stand alone.

Kazdin, A. E. 2011. Single-case research designs: Methods for clinical and applied settings . 2d ed. New York: Oxford Univ. Press.

A complete overview and description of single-case experimental design variants as well as information about data evaluation.

Kratochwill, T. R., and J. R. Levin, eds. 2014. Single-case intervention research: Methodological and statistical advances . New York: Routledge.

The authors describe in depth the methodological and analytic considerations necessary for designing and conducting research that uses a single-case experimental design. In addition, the text includes chapters from leaders in psychology and education who provide critical perspectives about the use of single-case experimental designs.

Ledford, J. R., and D. L. Gast, eds. 2018. Single case research methodology: Applications in special education and behavioral sciences . New York: Routledge.

Covers the research process from writing literature reviews, to designing, conducting, and evaluating single-case experimental design studies.

Riley-Tillman, T. C., and M. K. Burns. 2009. Evaluating education interventions: Single-case design for measuring response to intervention . New York: Guilford Press.

Focuses on accelerating uptake and use of single-case experimental designs in applied settings. This book provides a practical, “nuts and bolts” orientation to conducting single-case experimental design research.

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Single-Case Designs

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Single-case designs (also called single-case experimental designs) are system of research design strategies that can provide strong evidence of intervention effectiveness by using repeated measurement to establish each participant (or case) as his or her own control. The flexibility of the designs, and the focus on the individual as the unit of measurement, has led to an increased interest in the use of single-case design research in many areas of intervention research. The purpose of this chapter is to introduce the reader to the basic logic underlying the conduct and analysis of single-case design research by describing the fundamental features of this type of research, providing examples of several commonly used designs, and reviewing the guidelines for the visual analysis of single-case study data. Additionally, current areas of consensus and disagreement in the field of single-case design research will be discussed.

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Byiers, B. (2019). Single-Case Designs. In: Liamputtong, P. (eds) Handbook of Research Methods in Health Social Sciences. Springer, Singapore. https://doi.org/10.1007/978-981-10-5251-4_92

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Single-Case Experimental Design

Single-case experimental design, a versatile research methodology within psychology, holds particular significance in the field of school psychology. This article provides an overview of single-case experimental design, covering its definition, historical development, and key concepts. It delves into various types of single-case designs, including AB, ABA, and Multiple Baseline designs, illustrating their applications within school psychology. The article also explores data collection, analysis methods, and common challenges associated with this methodology. By highlighting its value in empirical research, this article underscores the enduring relevance of single-case experimental design in advancing the understanding and practice of school psychology.

Introduction

Single-case experimental design, a research methodology of profound importance in the realm of psychology, is characterized by its unique approach to investigating behavioral and psychological phenomena. Within this article, we will embark on a journey to explore the intricate facets of this research methodology and unravel its multifaceted applications, with a particular focus on its relevance in school psychology.

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Single-case experimental design, often referred to as “N of 1” research, is a methodology that centers on the in-depth examination of individual subjects or cases. Unlike traditional group-based designs, this approach allows researchers to closely study and understand the nuances of a single participant’s behavior, responses, and reactions over time. The precision and depth of insight offered by single-case experimental design have made it an invaluable tool in the field of psychology, facilitating both clinical and experimental research endeavors.

One of the most compelling aspects of this research methodology lies in its applicability to school psychology. In educational settings, understanding the unique needs and challenges of individual students is paramount, and single-case experimental design offers a tailored and systematic way to address these issues. Whether it involves assessing the effectiveness of an intervention for a specific learning disability or studying the impact of a behavior modification program for a student with special needs, single-case experimental design equips school psychologists with a powerful tool to make data-driven decisions and individualized educational plans.

Throughout this article, we will delve into the foundations of single-case experimental design, exploring its historical evolution, key concepts, and core terminology. We will also discuss the various types of single-case designs, including AB, ABA, and Multiple Baseline designs, illustrating their practical applications within the context of school psychology. Furthermore, the article will shed light on the data collection methods and the statistical techniques used for analysis, as well as the ethical considerations and challenges that researchers encounter in single-case experiments.

In sum, this article aims to provide an in-depth understanding of single-case experimental design and its pivotal role in advancing knowledge in psychology, particularly within the field of school psychology. As we embark on this exploration, it is evident that single-case experimental design serves as a bridge between rigorous scientific inquiry and the real-world needs of individuals, making it an indispensable asset in enhancing the quality of psychological research and practice.

Understanding Single-Case Experimental Design

Single-Case Experimental Design (SCED), often referred to as “N of 1” research, is a research methodology employed in psychology to investigate behavioral and psychological phenomena with an emphasis on the individual subject as the primary unit of analysis. The primary purpose of SCED is to meticulously study the behavior, responses, and changes within a single participant over time. Unlike traditional group-based research, SCED is tailored to the unique characteristics and needs of individual cases, enabling a more in-depth understanding of the variables under investigation.

The historical background of SCED can be traced back to the early 20th century when researchers like B.F. Skinner pioneered the development of operant conditioning and experimental analysis of behavior. Skinner’s work laid the groundwork for single-case experiments by emphasizing the importance of understanding the functional relations between behavior and environmental variables. Over the decades, SCED has evolved and gained prominence in various fields within psychology, notably in clinical and school psychology. Its relevance in school psychology is particularly noteworthy, as it offers a systematic and data-driven approach to address the diverse learning and behavioral needs of students. School psychologists use SCED to design and assess individualized interventions, evaluate the effectiveness of specific teaching strategies, and make informed decisions about special education programs.

Understanding SCED involves familiarity with key concepts and terminology that underpin the methodology. These terms include:

• Baseline: The initial phase of data collection where the participant’s behavior is measured before any intervention is introduced. Baseline data serve as a point of reference for assessing the impact of subsequent interventions.
• Intervention: The phase in which a specific treatment, manipulation, or condition is introduced to the participant. The goal of the intervention is to bring about a change in the target behavior.
• Dependent Variables: These are the behaviors or responses under investigation. They are the outcomes that researchers aim to measure and analyze for changes across different phases of the experiment.

Reliability and validity are critical considerations in SCED. Reliability refers to the consistency and stability of measurement. In SCED, it is crucial to ensure that data collection procedures are reliable, as any variability can affect the interpretation of results. Validity pertains to the accuracy and truthfulness of the data. Researchers must establish that the dependent variable measurements are valid and accurately reflect the behavior of interest. When these principles are applied in SCED, it enhances the scientific rigor and credibility of the research findings, which is essential in both clinical and school psychology contexts.

This foundation of key concepts and terminology serves as the basis for designing, conducting, and interpreting single-case experiments, ensuring that the methodology maintains high standards of precision and integrity in the pursuit of understanding individual behavior and psychological processes.

Types of Single-Case Experimental Designs

The AB Design is one of the fundamental single-case experimental designs, characterized by its simplicity and effectiveness. In an AB Design, the researcher observes and measures a single subject’s behavior during two distinct phases: the baseline (A) phase and the intervention (B) phase. During the baseline phase, the researcher collects data on the subject’s behavior without any intervention or treatment. This baseline data serve as a reference point to understand the natural or typical behavior of the individual. Following the baseline phase, the intervention or treatment is introduced, and data on the subject’s behavior are collected again. The AB Design allows for the comparison of baseline data with intervention data, enabling researchers to determine whether the introduced intervention had a noticeable impact on the individual’s behavior.

AB Designs find extensive application in school psychology. For instance, consider a scenario where a school psychologist wishes to assess the effectiveness of a time-management training program for a student with attention deficit hyperactivity disorder (ADHD). During the baseline phase, the psychologist observes the student’s on-task behavior in the absence of any specific time-management training. Subsequently, during the intervention phase, the psychologist implements the time-management program and measures the student’s on-task behavior again. By comparing the baseline and intervention data, the psychologist can evaluate the program’s efficacy in improving the student’s behavior.

The ABA Design is another prominent single-case experimental design characterized by the inclusion of a reversal (A) phase. In this design, the researcher initially collects baseline data (Phase A), introduces the intervention (Phase B), and then returns to the baseline conditions (Phase A). The ABA Design is significant because it provides an opportunity to assess the reversibility of the effects of the intervention. If the behavior returns to baseline levels during the second A phase, it suggests a strong relationship between the intervention and the observed changes in behavior.

In school psychology, the ABA Design offers valuable insights into the effectiveness of interventions for students with diverse needs. For instance, a school psychologist may use the ABA Design to evaluate a behavior modification program for a student with autism spectrum disorder (ASD). During the first baseline phase (A), the psychologist observes the student’s behavior patterns. Subsequently, in the intervention phase (B), a behavior modification program is implemented. If the student’s behavior shows positive changes, this suggests that the program is effective. Finally, during the second baseline phase (A), the psychologist can determine if the changes are reversible, which informs decisions regarding the program’s ongoing use or modification.

The Multiple Baseline Design is a versatile single-case experimental design that addresses challenges such as ethical concerns or logistical constraints that might limit the use of reversal designs. In this design, researchers stagger the introduction of the intervention across multiple behaviors, settings, or individuals. Each baseline and intervention phase is implemented at different times for each behavior, allowing researchers to establish a cause-and-effect relationship by demonstrating that the intervention corresponds with changes in the specific behavior under investigation.

Within school psychology, Multiple Baseline Designs offer particular utility when assessing interventions for students in complex or sensitive situations. For example, a school psychologist working with a student who displays challenging behaviors may choose to implement a Multiple Baseline Design. The psychologist can introduce a behavior intervention plan (BIP) for different target behaviors, such as aggression, noncompliance, and self-injury, at different times. By measuring and analyzing changes in behavior across these multiple behaviors, the psychologist can assess the effectiveness of the BIP and make informed decisions about its implementation across various behavioral concerns. This design is particularly valuable when ethical considerations prevent the reversal of an effective intervention, as it allows researchers to demonstrate the intervention’s impact without removing a beneficial treatment.

Conducting and Analyzing Single-Case Experiments

In single-case experiments, data collection and measurement are pivotal components that underpin the scientific rigor of the research. Data are typically collected through direct observation, self-reports, or the use of various measuring instruments, depending on the specific behavior or variable under investigation. To ensure reliability and validity, researchers meticulously define and operationalize the target behavior, specifying how it will be measured. This may involve the use of checklists, rating scales, video recordings, or other data collection tools. In school psychology research, systematic data collection is imperative to make informed decisions about interventions and individualized education plans (IEPs). It provides school psychologists with empirical evidence to track the progress of students, assess the effectiveness of interventions, and adapt strategies based on the collected data.

Visual analysis is a core element of interpreting data in single-case experiments. Researchers plot the data in graphs, creating visual representations of the behavior across different phases. By visually inspecting the data, researchers can identify patterns, trends, and changes in behavior. Visual analysis is particularly well-suited for detecting whether an intervention has had a noticeable effect.

In addition to visual analysis, statistical methods are occasionally employed in single-case experiments to enhance the rigor of analysis. These methods include effect size calculations and phase change calculations. Effect size measures, such as Cohen’s d or Tau-U, quantify the magnitude of change between the baseline and intervention phases, providing a quantitative understanding of the treatment’s impact. Phase change calculations determine the statistical significance of behavior change across different phases, aiding in the determination of whether the intervention had a meaningful effect.

Visual analysis and statistical methods complement each other, enabling researchers in school psychology to draw more robust conclusions about the efficacy of interventions. These methods are valuable in making data-driven decisions regarding students’ educational and behavioral progress.

Single-case experimental designs are not without their challenges and limitations. Researchers must grapple with issues such as the potential for confounding variables, limited generalizability to other cases, and the need for careful control of extraneous factors. In school psychology, these challenges are compounded by the dynamic and diverse nature of educational settings, making it essential for researchers to adapt the methodology to specific contexts and populations.

Moreover, ethical considerations loom large in school psychology research. Researchers must adhere to strict ethical guidelines when conducting single-case experiments involving students. Informed consent, confidentiality, and the well-being of the participants are paramount. Ethical considerations are especially critical when conducting research with vulnerable populations, such as students with disabilities or those in special education programs. The ethical conduct of research in school psychology is pivotal to maintaining trust and ensuring the welfare of students and their families.

In conclusion, the application of single-case experimental design in school psychology research is a powerful approach for addressing individualized educational and behavioral needs. By emphasizing systematic data collection, employing visual analysis and statistical methods, and navigating the inherent challenges and ethical considerations, researchers can contribute to the advancement of knowledge in this field while ensuring the well-being and progress of the students they serve.

In conclusion, this article has provided a comprehensive exploration of Single-Case Experimental Design (SCED) and its vital role within the domain of school psychology. Key takeaways from this article underscore the significance of SCED as a versatile and invaluable research methodology:

First and foremost, SCED is a methodological cornerstone for investigating individual behavior and psychological phenomena. Through meticulous observation and data collection, it enables researchers to gain deep insights into the idiosyncratic needs and responses of students in educational settings.

The significance of SCED in school psychology is pronounced. It empowers school psychologists to design and assess tailored interventions, evaluate the effectiveness of educational programs, and make data-driven decisions that enhance the quality of education for students with diverse needs. Whether it’s tracking progress, assessing the efficacy of behavioral interventions, or individualizing education plans, SCED plays an instrumental role in achieving these goals.

Furthermore, the article has illuminated three primary types of single-case experimental designs: AB, ABA, and Multiple Baseline. These designs offer the flexibility to investigate the effects of interventions and assess their reversibility when required. Such methods have a direct and tangible impact on the daily practices of school psychologists, allowing them to optimize support and educational strategies.

The importance of systematic data collection and measurement, the role of visual analysis and statistical methods in data interpretation, and the acknowledgment of ethical considerations in school psychology research have been underscored. These aspects collectively serve as the foundation of SCED, ensuring the integrity and reliability of research outcomes.

As we look toward the future, the potential developments in SCED are promising. Advances in technology, such as wearable devices and digital data collection tools, offer new possibilities for precise and efficient data gathering. Additionally, the integration of SCED with other research methodologies, such as mixed-methods research, holds the potential to provide a more comprehensive understanding of students’ educational experiences.

In summary, Single-Case Experimental Design is a pivotal research methodology that bridges the gap between rigorous scientific inquiry and the real-world needs of students in school psychology. Its power lies in its capacity to assess, refine, and individualize interventions and educational plans. The continued application and refinement of SCED in school psychology research promise to contribute significantly to the advancement of knowledge and the enhancement of educational outcomes for students of all backgrounds and abilities. As we move forward, the integration of SCED with emerging technologies and research paradigms will continue to shape the landscape of school psychology research, leading to more effective and tailored interventions for the benefit of students and the field as a whole.

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Methodology or method? A critical review of qualitative case study reports

Despite on-going debate about credibility, and reported limitations in comparison to other approaches, case study is an increasingly popular approach among qualitative researchers. We critically analysed the methodological descriptions of published case studies. Three high-impact qualitative methods journals were searched to locate case studies published in the past 5 years; 34 were selected for analysis. Articles were categorized as health and health services ( n= 12), social sciences and anthropology ( n= 7), or methods ( n= 15) case studies. The articles were reviewed using an adapted version of established criteria to determine whether adequate methodological justification was present, and if study aims, methods, and reported findings were consistent with a qualitative case study approach. Findings were grouped into five themes outlining key methodological issues: case study methodology or method, case of something particular and case selection, contextually bound case study, researcher and case interactions and triangulation, and study design inconsistent with methodology reported. Improved reporting of case studies by qualitative researchers will advance the methodology for the benefit of researchers and practitioners.

Case study research is an increasingly popular approach among qualitative researchers (Thomas, 2011 ). Several prominent authors have contributed to methodological developments, which has increased the popularity of case study approaches across disciplines (Creswell, 2013b ; Denzin & Lincoln, 2011b ; Merriam, 2009 ; Ragin & Becker, 1992 ; Stake, 1995 ; Yin, 2009 ). Current qualitative case study approaches are shaped by paradigm, study design, and selection of methods, and, as a result, case studies in the published literature vary. Differences between published case studies can make it difficult for researchers to define and understand case study as a methodology.

Experienced qualitative researchers have identified case study research as a stand-alone qualitative approach (Denzin & Lincoln, 2011b ). Case study research has a level of flexibility that is not readily offered by other qualitative approaches such as grounded theory or phenomenology. Case studies are designed to suit the case and research question and published case studies demonstrate wide diversity in study design. There are two popular case study approaches in qualitative research. The first, proposed by Stake ( 1995 ) and Merriam ( 2009 ), is situated in a social constructivist paradigm, whereas the second, by Yin ( 2012 ), Flyvbjerg ( 2011 ), and Eisenhardt ( 1989 ), approaches case study from a post-positivist viewpoint. Scholarship from both schools of inquiry has contributed to the popularity of case study and development of theoretical frameworks and principles that characterize the methodology.

The diversity of case studies reported in the published literature, and on-going debates about credibility and the use of case study in qualitative research practice, suggests that differences in perspectives on case study methodology may prevent researchers from developing a mutual understanding of practice and rigour. In addition, discussion about case study limitations has led some authors to query whether case study is indeed a methodology (Luck, Jackson, & Usher, 2006 ; Meyer, 2001 ; Thomas, 2010 ; Tight, 2010 ). Methodological discussion of qualitative case study research is timely, and a review is required to analyse and understand how this methodology is applied in the qualitative research literature. The aims of this study were to review methodological descriptions of published qualitative case studies, to review how the case study methodological approach was applied, and to identify issues that need to be addressed by researchers, editors, and reviewers. An outline of the current definitions of case study and an overview of the issues proposed in the qualitative methodological literature are provided to set the scene for the review.

Definitions of qualitative case study research

Case study research is an investigation and analysis of a single or collective case, intended to capture the complexity of the object of study (Stake, 1995 ). Qualitative case study research, as described by Stake ( 1995 ), draws together “naturalistic, holistic, ethnographic, phenomenological, and biographic research methods” in a bricoleur design, or in his words, “a palette of methods” (Stake, 1995 , pp. xi–xii). Case study methodology maintains deep connections to core values and intentions and is “particularistic, descriptive and heuristic” (Merriam, 2009 , p. 46).

As a study design, case study is defined by interest in individual cases rather than the methods of inquiry used. The selection of methods is informed by researcher and case intuition and makes use of naturally occurring sources of knowledge, such as people or observations of interactions that occur in the physical space (Stake, 1998 ). Thomas ( 2011 ) suggested that “analytical eclecticism” is a defining factor (p. 512). Multiple data collection and analysis methods are adopted to further develop and understand the case, shaped by context and emergent data (Stake, 1995 ). This qualitative approach “explores a real-life, contemporary bounded system (a case ) or multiple bounded systems (cases) over time, through detailed, in-depth data collection involving multiple sources of information … and reports a case description and case themes ” (Creswell, 2013b , p. 97). Case study research has been defined by the unit of analysis, the process of study, and the outcome or end product, all essentially the case (Merriam, 2009 ).

The case is an object to be studied for an identified reason that is peculiar or particular. Classification of the case and case selection procedures informs development of the study design and clarifies the research question. Stake ( 1995 ) proposed three types of cases and study design frameworks. These include the intrinsic case, the instrumental case, and the collective instrumental case. The intrinsic case is used to understand the particulars of a single case, rather than what it represents. An instrumental case study provides insight on an issue or is used to refine theory. The case is selected to advance understanding of the object of interest. A collective refers to an instrumental case which is studied as multiple, nested cases, observed in unison, parallel, or sequential order. More than one case can be simultaneously studied; however, each case study is a concentrated, single inquiry, studied holistically in its own entirety (Stake, 1995 , 1998 ).

Researchers who use case study are urged to seek out what is common and what is particular about the case. This involves careful and in-depth consideration of the nature of the case, historical background, physical setting, and other institutional and political contextual factors (Stake, 1998 ). An interpretive or social constructivist approach to qualitative case study research supports a transactional method of inquiry, where the researcher has a personal interaction with the case. The case is developed in a relationship between the researcher and informants, and presented to engage the reader, inviting them to join in this interaction and in case discovery (Stake, 1995 ). A postpositivist approach to case study involves developing a clear case study protocol with careful consideration of validity and potential bias, which might involve an exploratory or pilot phase, and ensures that all elements of the case are measured and adequately described (Yin, 2009 , 2012 ).

Current methodological issues in qualitative case study research

The future of qualitative research will be influenced and constructed by the way research is conducted, and by what is reviewed and published in academic journals (Morse, 2011 ). If case study research is to further develop as a principal qualitative methodological approach, and make a valued contribution to the field of qualitative inquiry, issues related to methodological credibility must be considered. Researchers are required to demonstrate rigour through adequate descriptions of methodological foundations. Case studies published without sufficient detail for the reader to understand the study design, and without rationale for key methodological decisions, may lead to research being interpreted as lacking in quality or credibility (Hallberg, 2013 ; Morse, 2011 ).

There is a level of artistic license that is embraced by qualitative researchers and distinguishes practice, which nurtures creativity, innovation, and reflexivity (Denzin & Lincoln, 2011b ; Morse, 2009 ). Qualitative research is “inherently multimethod” (Denzin & Lincoln, 2011a , p. 5); however, with this creative freedom, it is important for researchers to provide adequate description for methodological justification (Meyer, 2001 ). This includes paradigm and theoretical perspectives that have influenced study design. Without adequate description, study design might not be understood by the reader, and can appear to be dishonest or inaccurate. Reviewers and readers might be confused by the inconsistent or inappropriate terms used to describe case study research approach and methods, and be distracted from important study findings (Sandelowski, 2000 ). This issue extends beyond case study research, and others have noted inconsistencies in reporting of methodology and method by qualitative researchers. Sandelowski ( 2000 , 2010 ) argued for accurate identification of qualitative description as a research approach. She recommended that the selected methodology should be harmonious with the study design, and be reflected in methods and analysis techniques. Similarly, Webb and Kevern ( 2000 ) uncovered inconsistencies in qualitative nursing research with focus group methods, recommending that methodological procedures must cite seminal authors and be applied with respect to the selected theoretical framework. Incorrect labelling using case study might stem from the flexibility in case study design and non-directional character relative to other approaches (Rosenberg & Yates, 2007 ). Methodological integrity is required in design of qualitative studies, including case study, to ensure study rigour and to enhance credibility of the field (Morse, 2011 ).

Case study has been unnecessarily devalued by comparisons with statistical methods (Eisenhardt, 1989 ; Flyvbjerg, 2006 , 2011 ; Jensen & Rodgers, 2001 ; Piekkari, Welch, & Paavilainen, 2009 ; Tight, 2010 ; Yin, 1999 ). It is reputed to be the “the weak sibling” in comparison to other, more rigorous, approaches (Yin, 2009 , p. xiii). Case study is not an inherently comparative approach to research. The objective is not statistical research, and the aim is not to produce outcomes that are generalizable to all populations (Thomas, 2011 ). Comparisons between case study and statistical research do little to advance this qualitative approach, and fail to recognize its inherent value, which can be better understood from the interpretive or social constructionist viewpoint of other authors (Merriam, 2009 ; Stake, 1995 ). Building on discussions relating to “fuzzy” (Bassey, 2001 ), or naturalistic generalizations (Stake, 1978 ), or transference of concepts and theories (Ayres, Kavanaugh, & Knafl, 2003 ; Morse et al., 2011 ) would have more relevance.

Case study research has been used as a catch-all design to justify or add weight to fundamental qualitative descriptive studies that do not fit with other traditional frameworks (Merriam, 2009 ). A case study has been a “convenient label for our research—when we ‘can't think of anything ‘better”—in an attempt to give it [qualitative methodology] some added respectability” (Tight, 2010 , p. 337). Qualitative case study research is a pliable approach (Merriam, 2009 ; Meyer, 2001 ; Stake, 1995 ), and has been likened to a “curious methodological limbo” (Gerring, 2004 , p. 341) or “paradigmatic bridge” (Luck et al., 2006 , p. 104), that is on the borderline between postpositivist and constructionist interpretations. This has resulted in inconsistency in application, which indicates that flexibility comes with limitations (Meyer, 2001 ), and the open nature of case study research might be off-putting to novice researchers (Thomas, 2011 ). The development of a well-(in)formed theoretical framework to guide a case study should improve consistency, rigour, and trust in studies published in qualitative research journals (Meyer, 2001 ).

Assessment of rigour

The purpose of this study was to analyse the methodological descriptions of case studies published in qualitative methods journals. To do this we needed to develop a suitable framework, which used existing, established criteria for appraising qualitative case study research rigour (Creswell, 2013b ; Merriam, 2009 ; Stake, 1995 ). A number of qualitative authors have developed concepts and criteria that are used to determine whether a study is rigorous (Denzin & Lincoln, 2011b ; Lincoln, 1995 ; Sandelowski & Barroso, 2002 ). The criteria proposed by Stake ( 1995 ) provide a framework for readers and reviewers to make judgements regarding case study quality, and identify key characteristics essential for good methodological rigour. Although each of the factors listed in Stake's criteria could enhance the quality of a qualitative research report, in Table I we present an adapted criteria used in this study, which integrates more recent work by Merriam ( 2009 ) and Creswell ( 2013b ). Stake's ( 1995 ) original criteria were separated into two categories. The first list of general criteria is “relevant for all qualitative research.” The second list, “high relevance to qualitative case study research,” was the criteria that we decided had higher relevance to case study research. This second list was the main criteria used to assess the methodological descriptions of the case studies reviewed. The complete table has been preserved so that the reader can determine how the original criteria were adapted.

Framework for assessing quality in qualitative case study research.

Adapted from Stake ( 1995 , p. 131).

Study design

The critical review method described by Grant and Booth ( 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, 2009 , p. 93). A critical review is used to develop existing, or produce new, hypotheses or models. This is different to systematic reviews that answer clinical questions. It is used to evaluate existing research and competing ideas, to provide a “launch pad” for conceptual development and “subsequent testing” (Grant & Booth, 2009 , p. 93).

Qualitative methods journals were located by a search of the 2011 ISI Journal Citation Reports in Social Science, via the database Web of Knowledge (see m.webofknowledge.com). No “qualitative research methods” category existed in the citation reports; therefore, a search of all categories was performed using the term “qualitative.” In Table II , we present the qualitative methods journals located, ranked by impact factor. The highest ranked journals were selected for searching. We acknowledge that the impact factor ranking system might not be the best measure of journal quality (Cheek, Garnham, & Quan, 2006 ); however, this was the most appropriate and accessible method available.

International Journal of Qualitative Studies on Health and Well-being.

Search strategy

In March 2013, searches of the journals, Qualitative Health Research , Qualitative Research , and Qualitative Inquiry were completed to retrieve studies with “case study” in the abstract field. The search was limited to the past 5 years (1 January 2008 to 1 March 2013). The objective was to locate published qualitative case studies suitable for assessment using the adapted criterion. Viewpoints, commentaries, and other article types were excluded from review. Title and abstracts of the 45 retrieved articles were read by the first author, who identified 34 empirical case studies for review. All authors reviewed the 34 studies to confirm selection and categorization. In Table III , we present the 34 case studies grouped by journal, and categorized by research topic, including health sciences, social sciences and anthropology, and methods research. There was a discrepancy in categorization of one article on pedagogy and a new teaching method published in Qualitative Inquiry (Jorrín-Abellán, Rubia-Avi, Anguita-Martínez, Gómez-Sánchez, & Martínez-Mones, 2008 ). Consensus was to allocate to the methods category.

Outcomes of search of qualitative methods journals.

In Table III , the number of studies located, and final numbers selected for review have been reported. Qualitative Health Research published the most empirical case studies ( n= 16). In the health category, there were 12 case studies of health conditions, health services, and health policy issues, all published in Qualitative Health Research . Seven case studies were categorized as social sciences and anthropology research, which combined case study with biography and ethnography methodologies. All three journals published case studies on methods research to illustrate a data collection or analysis technique, methodological procedure, or related issue.

The methodological descriptions of 34 case studies were critically reviewed using the adapted criteria. All articles reviewed contained a description of study methods; however, the length, amount of detail, and position of the description in the article varied. Few studies provided an accurate description and rationale for using a qualitative case study approach. In the 34 case studies reviewed, three described a theoretical framework informed by Stake ( 1995 ), two by Yin ( 2009 ), and three provided a mixed framework informed by various authors, which might have included both Yin and Stake. Few studies described their case study design, or included a rationale that explained why they excluded or added further procedures, and whether this was to enhance the study design, or to better suit the research question. In 26 of the studies no reference was provided to principal case study authors. From reviewing the description of methods, few authors provided a description or justification of case study methodology that demonstrated how their study was informed by the methodological literature that exists on this approach.

The methodological descriptions of each study were reviewed using the adapted criteria, and the following issues were identified: case study methodology or method; case of something particular and case selection; contextually bound case study; researcher and case interactions and triangulation; and, study design inconsistent with methodology. An outline of how the issues were developed from the critical review is provided, followed by a discussion of how these relate to the current methodological literature.

Case study methodology or method

A third of the case studies reviewed appeared to use a case report method, not case study methodology as described by principal authors (Creswell, 2013b ; Merriam, 2009 ; Stake, 1995 ; Yin, 2009 ). Case studies were identified as a case report because of missing methodological detail and by review of the study aims and purpose. These reports presented data for small samples of no more than three people, places or phenomenon. Four studies, or “case reports” were single cases selected retrospectively from larger studies (Bronken, Kirkevold, Martinsen, & Kvigne, 2012 ; Coltart & Henwood, 2012 ; Hooghe, Neimeyer, & Rober, 2012 ; Roscigno et al., 2012 ). Case reports were not a case of something, instead were a case demonstration or an example presented in a report. These reports presented outcomes, and reported on how the case could be generalized. Descriptions focussed on the phenomena, rather than the case itself, and did not appear to study the case in its entirety.

Case reports had minimal in-text references to case study methodology, and were informed by other qualitative traditions or secondary sources (Adamson & Holloway, 2012 ; Buzzanell & D'Enbeau, 2009 ; Nagar-Ron & Motzafi-Haller, 2011 ). This does not suggest that case study methodology cannot be multimethod, however, methodology should be consistent in design, be clearly described (Meyer, 2001 ; Stake, 1995 ), and maintain focus on the case (Creswell, 2013b ).

To demonstrate how case reports were identified, three examples are provided. The first, Yeh ( 2013 ) described their study as, “the examination of the emergence of vegetarianism in Victorian England serves as a case study to reveal the relationships between boundaries and entities” (p. 306). The findings were a historical case report, which resulted from an ethnographic study of vegetarianism. Cunsolo Willox, Harper, Edge, ‘My Word’: Storytelling and Digital Media Lab, and Rigolet Inuit Community Government (2013) used “a case study that illustrates the usage of digital storytelling within an Inuit community” (p. 130). This case study reported how digital storytelling can be used with indigenous communities as a participatory method to illuminate the benefits of this method for other studies. This “case study was conducted in the Inuit community” but did not include the Inuit community in case analysis (Cunsolo Willox et al., 2013 , p. 130). Bronken et al. ( 2012 ) provided a single case report to demonstrate issues observed in a larger clinical study of aphasia and stroke, without adequate case description or analysis.

Case study of something particular and case selection

Case selection is a precursor to case analysis, which needs to be presented as a convincing argument (Merriam, 2009 ). Descriptions of the case were often not adequate to ascertain why the case was selected, or whether it was a particular exemplar or outlier (Thomas, 2011 ). In a number of case studies in the health and social science categories, it was not explicit whether the case was of something particular, or peculiar to their discipline or field (Adamson & Holloway, 2012 ; Bronken et al., 2012 ; Colón-Emeric et al., 2010 ; Jackson, Botelho, Welch, Joseph, & Tennstedt, 2012 ; Mawn et al., 2010 ; Snyder-Young, 2011 ). There were exceptions in the methods category ( Table III ), where cases were selected by researchers to report on a new or innovative method. The cases emerged through heuristic study, and were reported to be particular, relative to the existing methods literature (Ajodhia-Andrews & Berman, 2009 ; Buckley & Waring, 2013 ; Cunsolo Willox et al., 2013 ; De Haene, Grietens, & Verschueren, 2010 ; Gratton & O'Donnell, 2011 ; Sumsion, 2013 ; Wimpenny & Savin-Baden, 2012 ).

Case selection processes were sometimes insufficient to understand why the case was selected from the global population of cases, or what study of this case would contribute to knowledge as compared with other possible cases (Adamson & Holloway, 2012 ; Bronken et al., 2012 ; Colón-Emeric et al., 2010 ; Jackson et al., 2012 ; Mawn et al., 2010 ). In two studies, local cases were selected (Barone, 2010 ; Fourie & Theron, 2012 ) because the researcher was familiar with and had access to the case. Possible limitations of a convenience sample were not acknowledged. Purposeful sampling was used to recruit participants within the case of one study, but not of the case itself (Gallagher et al., 2013 ). Random sampling was completed for case selection in two studies (Colón-Emeric et al., 2010 ; Jackson et al., 2012 ), which has limited meaning in interpretive qualitative research.

To demonstrate how researchers provided a good justification for the selection of case study approaches, four examples are provided. The first, cases of residential care homes, were selected because of reported occurrences of mistreatment, which included residents being locked in rooms at night (Rytterström, Unosson, & Arman, 2013 ). Roscigno et al. ( 2012 ) selected cases of parents who were admitted for early hospitalization in neonatal intensive care with a threatened preterm delivery before 26 weeks. Hooghe et al. ( 2012 ) used random sampling to select 20 couples that had experienced the death of a child; however, the case study was of one couple and a particular metaphor described only by them. The final example, Coltart and Henwood ( 2012 ), provided a detailed account of how they selected two cases from a sample of 46 fathers based on personal characteristics and beliefs. They described how the analysis of the two cases would contribute to their larger study on first time fathers and parenting.

Contextually bound case study

The limits or boundaries of the case are a defining factor of case study methodology (Merriam, 2009 ; Ragin & Becker, 1992 ; Stake, 1995 ; Yin, 2009 ). Adequate contextual description is required to understand the setting or context in which the case is revealed. In the health category, case studies were used to illustrate a clinical phenomenon or issue such as compliance and health behaviour (Colón-Emeric et al., 2010 ; D'Enbeau, Buzzanell, & Duckworth, 2010 ; Gallagher et al., 2013 ; Hooghe et al., 2012 ; Jackson et al., 2012 ; Roscigno et al., 2012 ). In these case studies, contextual boundaries, such as physical and institutional descriptions, were not sufficient to understand the case as a holistic system, for example, the general practitioner (GP) clinic in Gallagher et al. ( 2013 ), or the nursing home in Colón-Emeric et al. ( 2010 ). Similarly, in the social science and methods categories, attention was paid to some components of the case context, but not others, missing important information required to understand the case as a holistic system (Alexander, Moreira, & Kumar, 2012 ; Buzzanell & D'Enbeau, 2009 ; Nairn & Panelli, 2009 ; Wimpenny & Savin-Baden, 2012 ).

In two studies, vicarious experience or vignettes (Nairn & Panelli, 2009 ) and images (Jorrín-Abellán et al., 2008 ) were effective to support description of context, and might have been a useful addition for other case studies. Missing contextual boundaries suggests that the case might not be adequately defined. Additional information, such as the physical, institutional, political, and community context, would improve understanding of the case (Stake, 1998 ). In Boxes 1 and 2 , we present brief synopses of two studies that were reviewed, which demonstrated a well bounded case. In Box 1 , Ledderer ( 2011 ) used a qualitative case study design informed by Stake's tradition. In Box 2 , Gillard, Witt, and Watts ( 2011 ) were informed by Yin's tradition. By providing a brief outline of the case studies in Boxes 1 and 2 , we demonstrate how effective case boundaries can be constructed and reported, which may be of particular interest to prospective case study researchers.

Article synopsis of case study research using Stake's tradition

Ledderer ( 2011 ) used a qualitative case study research design, informed by modern ethnography. The study is bounded to 10 general practice clinics in Denmark, who had received federal funding to implement preventative care services based on a Motivational Interviewing intervention. The researcher question focussed on “why is it so difficult to create change in medical practice?” (Ledderer, 2011 , p. 27). The study context was adequately described, providing detail on the general practitioner (GP) clinics and relevant political and economic influences. Methodological decisions are described in first person narrative, providing insight on researcher perspectives and interaction with the case. Forty-four interviews were conducted, which focussed on how GPs conducted consultations, and the form, nature and content, rather than asking their opinion or experience (Ledderer, 2011 , p. 30). The duration and intensity of researcher immersion in the case enhanced depth of description and trustworthiness of study findings. Analysis was consistent with Stake's tradition, and the researcher provided examples of inquiry techniques used to challenge assumptions about emerging themes. Several other seminal qualitative works were cited. The themes and typology constructed are rich in narrative data and storytelling by clinic staff, demonstrating individual clinic experiences as well as shared meanings and understandings about changing from a biomedical to psychological approach to preventative health intervention. Conclusions make note of social and cultural meanings and lessons learned, which might not have been uncovered using a different methodology.

Article synopsis of case study research using Yin's tradition

Gillard et al. ( 2011 ) study of camps for adolescents living with HIV/AIDs provided a good example of Yin's interpretive case study approach. The context of the case is bounded by the three summer camps of which the researchers had prior professional involvement. A case study protocol was developed that used multiple methods to gather information at three data collection points coinciding with three youth camps (Teen Forum, Discover Camp, and Camp Strong). Gillard and colleagues followed Yin's ( 2009 ) principles, using a consistent data protocol that enhanced cross-case analysis. Data described the young people, the camp physical environment, camp schedule, objectives and outcomes, and the staff of three youth camps. The findings provided a detailed description of the context, with less detail of individual participants, including insight into researcher's interpretations and methodological decisions throughout the data collection and analysis process. Findings provided the reader with a sense of “being there,” and are discovered through constant comparison of the case with the research issues; the case is the unit of analysis. There is evidence of researcher immersion in the case, and Gillard reports spending significant time in the field in a naturalistic and integrated youth mentor role.

This case study is not intended to have a significant impact on broader health policy, although does have implications for health professionals working with adolescents. Study conclusions will inform future camps for young people with chronic disease, and practitioners are able to compare similarities between this case and their own practice (for knowledge translation). No limitations of this article were reported. Limitations related to publication of this case study were that it was 20 pages long and used three tables to provide sufficient description of the camp and program components, and relationships with the research issue.

Researcher and case interactions and triangulation

Researcher and case interactions and transactions are a defining feature of case study methodology (Stake, 1995 ). Narrative stories, vignettes, and thick description are used to provoke vicarious experience and a sense of being there with the researcher in their interaction with the case. Few of the case studies reviewed provided details of the researcher's relationship with the case, researcher–case interactions, and how these influenced the development of the case study (Buzzanell & D'Enbeau, 2009 ; D'Enbeau et al., 2010 ; Gallagher et al., 2013 ; Gillard et al., 2011 ; Ledderer, 2011 ; Nagar-Ron & Motzafi-Haller, 2011 ). The role and position of the researcher needed to be self-examined and understood by readers, to understand how this influenced interactions with participants, and to determine what triangulation is needed (Merriam, 2009 ; Stake, 1995 ).

Gillard et al. ( 2011 ) provided a good example of triangulation, comparing data sources in a table (p. 1513). Triangulation of sources was used to reveal as much depth as possible in the study by Nagar-Ron and Motzafi-Haller ( 2011 ), while also enhancing confirmation validity. There were several case studies that would have benefited from improved range and use of data sources, and descriptions of researcher–case interactions (Ajodhia-Andrews & Berman, 2009 ; Bronken et al., 2012 ; Fincham, Scourfield, & Langer, 2008 ; Fourie & Theron, 2012 ; Hooghe et al., 2012 ; Snyder-Young, 2011 ; Yeh, 2013 ).

Study design inconsistent with methodology

Good, rigorous case studies require a strong methodological justification (Meyer, 2001 ) and a logical and coherent argument that defines paradigm, methodological position, and selection of study methods (Denzin & Lincoln, 2011b ). Methodological justification was insufficient in several of the studies reviewed (Barone, 2010 ; Bronken et al., 2012 ; Hooghe et al., 2012 ; Mawn et al., 2010 ; Roscigno et al., 2012 ; Yeh, 2013 ). This was judged by the absence, or inadequate or inconsistent reference to case study methodology in-text.

In six studies, the methodological justification provided did not relate to case study. There were common issues identified. Secondary sources were used as primary methodological references indicating that study design might not have been theoretically sound (Colón-Emeric et al., 2010 ; Coltart & Henwood, 2012 ; Roscigno et al., 2012 ; Snyder-Young, 2011 ). Authors and sources cited in methodological descriptions were inconsistent with the actual study design and practices used (Fourie & Theron, 2012 ; Hooghe et al., 2012 ; Jorrín-Abellán et al., 2008 ; Mawn et al., 2010 ; Rytterström et al., 2013 ; Wimpenny & Savin-Baden, 2012 ). This occurred when researchers cited Stake or Yin, or both (Mawn et al., 2010 ; Rytterström et al., 2013 ), although did not follow their paradigmatic or methodological approach. In 26 studies there were no citations for a case study methodological approach.

The findings of this study have highlighted a number of issues for researchers. A considerable number of case studies reviewed were missing key elements that define qualitative case study methodology and the tradition cited. A significant number of studies did not provide a clear methodological description or justification relevant to case study. Case studies in health and social sciences did not provide sufficient information for the reader to understand case selection, and why this case was chosen above others. The context of the cases were not described in adequate detail to understand all relevant elements of the case context, which indicated that cases may have not been contextually bounded. There were inconsistencies between reported methodology, study design, and paradigmatic approach in case studies reviewed, which made it difficult to understand the study methodology and theoretical foundations. These issues have implications for methodological integrity and honesty when reporting study design, which are values of the qualitative research tradition and are ethical requirements (Wager & Kleinert, 2010a ). Poorly described methodological descriptions may lead the reader to misinterpret or discredit study findings, which limits the impact of the study, and, as a collective, hinders advancements in the broader qualitative research field.

The issues highlighted in our review build on current debates in the case study literature, and queries about the value of this methodology. Case study research can be situated within different paradigms or designed with an array of methods. In order to maintain the creativity and flexibility that is valued in this methodology, clearer descriptions of paradigm and theoretical position and methods should be provided so that study findings are not undervalued or discredited. Case study research is an interdisciplinary practice, which means that clear methodological descriptions might be more important for this approach than other methodologies that are predominantly driven by fewer disciplines (Creswell, 2013b ).

Authors frequently omit elements of methodologies and include others to strengthen study design, and we do not propose a rigid or purist ideology in this paper. On the contrary, we encourage new ideas about using case study, together with adequate reporting, which will advance the value and practice of case study. The implications of unclear methodological descriptions in the studies reviewed were that study design appeared to be inconsistent with reported methodology, and key elements required for making judgements of rigour were missing. It was not clear whether the deviations from methodological tradition were made by researchers to strengthen the study design, or because of misinterpretations. Morse ( 2011 ) recommended that innovations and deviations from practice are best made by experienced researchers, and that a novice might be unaware of the issues involved with making these changes. To perpetuate the tradition of case study research, applications in the published literature should have consistencies with traditional methodological constructions, and deviations should be described with a rationale that is inherent in study conduct and findings. Providing methodological descriptions that demonstrate a strong theoretical foundation and coherent study design will add credibility to the study, while ensuring the intrinsic meaning of case study is maintained.

The value of this review is that it contributes to discussion of whether case study is a methodology or method. We propose possible reasons why researchers might make this misinterpretation. Researchers may interchange the terms methods and methodology, and conduct research without adequate attention to epistemology and historical tradition (Carter & Little, 2007 ; Sandelowski, 2010 ). If the rich meaning that naming a qualitative methodology brings to the study is not recognized, a case study might appear to be inconsistent with the traditional approaches described by principal authors (Creswell, 2013a ; Merriam, 2009 ; Stake, 1995 ; Yin, 2009 ). If case studies are not methodologically and theoretically situated, then they might appear to be a case report.

Case reports are promoted by university and medical journals as a method of reporting on medical or scientific cases; guidelines for case reports are publicly available on websites ( http://www.hopkinsmedicine.org/institutional_review_board/guidelines_policies/guidelines/case_report.html ). The various case report guidelines provide a general criteria for case reports, which describes that this form of report does not meet the criteria of research, is used for retrospective analysis of up to three clinical cases, and is primarily illustrative and for educational purposes. Case reports can be published in academic journals, but do not require approval from a human research ethics committee. Traditionally, case reports describe a single case, to explain how and what occurred in a selected setting, for example, to illustrate a new phenomenon that has emerged from a larger study. A case report is not necessarily particular or the study of a case in its entirety, and the larger study would usually be guided by a different research methodology.

This description of a case report is similar to what was provided in some studies reviewed. This form of report lacks methodological grounding and qualities of research rigour. The case report has publication value in demonstrating an example and for dissemination of knowledge (Flanagan, 1999 ). However, case reports have different meaning and purpose to case study, which needs to be distinguished. Findings of our review suggest that the medical understanding of a case report has been confused with qualitative case study approaches.

In this review, a number of case studies did not have methodological descriptions that included key characteristics of case study listed in the adapted criteria, and several issues have been discussed. There have been calls for improvements in publication quality of qualitative research (Morse, 2011 ), and for improvements in peer review of submitted manuscripts (Carter & Little, 2007 ; Jasper, Vaismoradi, Bondas, & Turunen, 2013 ). The challenging nature of editor and reviewers responsibilities are acknowledged in the literature (Hames, 2013 ; Wager & Kleinert, 2010b ); however, review of case study methodology should be prioritized because of disputes on methodological value.

Authors using case study approaches are recommended to describe their theoretical framework and methods clearly, and to seek and follow specialist methodological advice when needed (Wager & Kleinert, 2010a ). Adequate page space for case study description would contribute to better publications (Gillard et al., 2011 ). Capitalizing on the ability to publish complementary resources should be considered.

Limitations of the review

There is a level of subjectivity involved in this type of review and this should be considered when interpreting study findings. Qualitative methods journals were selected because the aims and scope of these journals are to publish studies that contribute to methodological discussion and development of qualitative research. Generalist health and social science journals were excluded that might have contained good quality case studies. Journals in business or education were also excluded, although a review of case studies in international business journals has been published elsewhere (Piekkari et al., 2009 ).

The criteria used to assess the quality of the case studies were a set of qualitative indicators. A numerical or ranking system might have resulted in different results. Stake's ( 1995 ) criteria have been referenced elsewhere, and was deemed the best available (Creswell, 2013b ; Crowe et al., 2011 ). Not all qualitative studies are reported in a consistent way and some authors choose to report findings in a narrative form in comparison to a typical biomedical report style (Sandelowski & Barroso, 2002 ), if misinterpretations were made this may have affected the review.

Case study research is an increasingly popular approach among qualitative researchers, which provides methodological flexibility through the incorporation of different paradigmatic positions, study designs, and methods. However, whereas flexibility can be an advantage, a myriad of different interpretations has resulted in critics questioning the use of case study as a methodology. Using an adaptation of established criteria, we aimed to identify and assess the methodological descriptions of case studies in high impact, qualitative methods journals. Few articles were identified that applied qualitative case study approaches as described by experts in case study design. There were inconsistencies in methodology and study design, which indicated that researchers were confused whether case study was a methodology or a method. Commonly, there appeared to be confusion between case studies and case reports. Without clear understanding and application of the principles and key elements of case study methodology, there is a risk that the flexibility of the approach will result in haphazard reporting, and will limit its global application as a valuable, theoretically supported methodology that can be rigorously applied across disciplines and fields.

Conflict of interest and funding

The authors have not received any funding or benefits from industry or elsewhere to conduct this study.

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15.1 The basics of single-system research design

Learning objectives.

Learners will be able to…

• Identify why social workers might use single-subjects design.
• Describe the two stages of single-subjects design.
• Previously imported from Mauldin 2019
• WRITTEN BY TRMC

Single-systems research design, sometimes called single-subject or single-case research design, is distinct from other research methodologies in that, as its name indicates, only one person, group, policy, etc. (i.e., system) is being studied. Because clinical social work often involves one-on-one practice, single-subjects designs are often used by social workers to ensure that their interventions are having a positive effect. Single-subjects designs are used to demonstrate that social work intervention has its intended effects.  Single-subjects designs are most compatible with clinical modalities such as cognitive-behavioral therapy which incorporate as part of treatment client self-monitoring, clinician data analysis, and quantitative measurement. It is routine in this therapeutic model to track, for example, the number of intrusive thoughts experienced between counseling sessions. Moreover, practitioners spend time each session reviewing changes in patterns during the therapeutic process, using it to evaluate and fine-tune the therapeutic approach. Although researchers have used single-subjects designs with less positivist therapies, such as narrative therapy, the single-subjects design is generally used in therapies with more quantifiable outcomes. The results of single-systems studies help ensure that social workers are not providing useless or counterproductive interventions to their clients.

By definition, single-systems design only attempts to explain causality in one case; therefore the results are not generalizable. Because their results are not generalizable, single-systems studies do not meet the strict definition of research , and are generally used in practice settings only. While the results will not be generalizable, they do provide important insight into the effectiveness of clinical interventions. Social work researchers teaching in BSW and MSW programs will teach single-systems design to their students, and on occasion may publish results of single systems research design to further knowledge about interventions.

The two main stages of single-systems research design

Single-systems designs follow the logic of experimental design by attempting to compare conditions when no intervention or treatment is applied to conditions when there is an intervention. To do this, SSRDs involve repeated measurements over time, usually in two stages and attempts to identify changes in a behavioral outcome (i.e., the dependent variable) s a result of an intervention, program, or treatment (i.e., the independent variable). The dependent variable is measured repeatedly during two distinct phases: the baseline stage and the treatment stage .

The baseline stage is the period of time before the intervention starts. During the baseline stage, the social worker is collecting data about the problem the treatment is hoping to address.  For example, a person with substance use issues may binge drink on the weekends but cut down their drinking during the work week.  A social worker might ask the client to record the number of drinks that they consume each day.  By looking at this, we could evaluate the level of alcohol consumption.  For other clients, the social worker might assess other indicators, such as the number of arguments the client had when they were drinking or whether or not the client blacked out as a result of drinking.  Whatever measure is used to assess the targeted problem, that measure is the dependent variable in the single-subjects design.

The baseline stage should last until a pattern emerges in the dependent variable.  This requires at least three different occasions of measurement, but it can often take longer.  During the baseline stage, the social worker looks for one of three types of patterns (Engel & Schutt, 2016).  The dependent variable may (1) be stable over time, (2) exhibit a trend where it is increasing or decreasing over time, or (3) have a cycle of increasing and decreasing that is repeated over time.  Establishing a pattern can prove difficult in clients whose behaviors vary widely.

Ideally, social workers would start measurement for the baseline stage before starting the intervention. This provides the opportunity to determine the baseline pattern.  Unfortunately, that may be impractical or unethical to do in practice if it entails withholding important treatment. In that case, a retrospective baseline can be attained by asking the client to recollect data from before the intervention started.  The drawback to this is the information is likely to be less reliable than a baseline data recorded in real time. The baseline stage is important because with only one subject, there is no control group. Thus, we have to see if our intervention is effective by comparing the client before treatment to and during and after treatment.  In this way, the baseline stage provides the same type of information as a control group — what it looks like when there is not treatment given.

The next stage is the treatment stage , and it refers to the time in which the treatment is administered by the social worker. Repeated measurements are taken during this stage to see if there is change in the dependent variable during treatment.

One way to analyze the data from a single-subjects design is to visually examine a graphical representation of the results.  An example of a graph from a single-subjects design is shown in Figure 11.1.  The x -axis is time, as measured in months. The y -axis is the measure of the problem we’re trying to change (i.e., the dependent variable).

In Figure 11.1, the y -axis is caseload size. From 1998 to July of 1991, there was no treatment. This is the baseline phase, and we can examine it for a pattern. There was an upward trend at the beginning of the baseline phase, but it looks as if the caseloads began to decrease around October 1989. The vertical line indicates when the intervention began (around July 1991). Once the intervention occurred, the downward trend continues. In this case, it is not clear if there was a change due to the intervention or if it was a continuation of a trend that began in October of 1989.

Key Takeaways

• Social workers conduct single-subjects research designs to make sure their interventions are effective.
• Single-subjects designs use repeated measures before and during treatment to assess the effectiveness of an intervention.
• Single-subjects designs often use a graphical representation of numerical data to look for patterns.

a systematic investigation, including development, testing, and. evaluation, designed to develop or contribute to generalizable knowledge

The stage in single-subjects design in which a baseline level or pattern of the dependent variable is established

The stage in single subjects research design in which the treatment or intervention is delivered

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Justices Examine Use of a Law to Charge Jan. 6 Rioters

The questioning explored the gravity of the assault and whether prosecutors had stretched the law to reach members of the mob responsible for the attack.

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Abbie VanSickle

The implications for the court’s decision in today’s Jan. 6 case could eliminate some of the federal charges that former President Donald J. Trump is facing for his role in the plot to subvert the 2020 election. It could also jeopardize hundreds of Jan. 6 prosecutions.

Adam Liptak

Reporting from Washington

Trump allies are using this case to try to reframe the Jan. 6 attack.

Lawmakers allied with former President Trump are using a case before the Supreme Court as part of their effort to reframe the events of Jan. 6, 2021, as a political protest, not a violent assault on the Capitol in which violence disrupted Congress and lawmakers fled.

The case before the Supreme Court, focused on the text of a statute used to charge some participants, also has the potential to determine the very meaning of Jan. 6. Briefs from Mr. Trump’s supporters echo the former president’s embrace of the rioters during his campaign events.

Senator Tom Cotton of Arkansas, Representative Jim Jordan of Ohio and other Republican lawmakers said in one brief that “the Department of Justice and D.C. juries have readily attributed immorality to the genuine belief of many Jan. 6 defendants that there was fraud during the 2020 presidential election.”

Protests are part of the fabric of politics, they wrote, adding that the prosecutors’ interpretation of the statute would have applied to a peaceful rally led by the Rev. Dr. Martin Luther King Jr.

“Advocacy groups throughout history have organized trips to Washington timed to congressional or executive consideration of favored items,” the lawmakers wrote in the brief before going on to quote from a magazine article. “Most famously, the 1963 civil rights ‘March on Washington’ ‘was designed to force President Kennedy to support the Civil Rights Act’ then pending in Congress.”

The brief also discussed other protests, including the disruption of the Supreme Court confirmation hearing of Justice Brett M. Kavanaugh, and praised the Trump administration’s restraint.

“Those actions by protesters were highly improper and certainly were criminal,” the brief said of the Kavanaugh protest. “But President Trump’s Department of Justice did not adopt the strained view that those protesters should be charged” under the statute at issue in the new case.

The Biden administration, in its main brief , devoted a paragraph to the critique, drawing several distinctions. The law, the brief said, “covers acts that hinder a proceeding — not acts, like lobbying or peaceful protest, that are not readily characterized as rising to the level of obstruction or that independently enjoy protection under the First Amendment.”

The brief added that the law applied only to conduct directed at a specific proceeding and required proof that the defendant had acted corruptly.

Critics of Mr. Trump — including J. Michael Luttig, a conservative former appeals court judge, and John Danforth, a Republican former senator from Missouri — countered that the comparisons pressed by Mr. Cotton and Mr. Jordan were profoundly misplaced.

“There is simply no historical comparison between the consequences of criminal acts in opposition to the election of a new president — as illustrated by both our Civil War and the Jan. 6, 2021, invasion — and the ‘what about’ examples discussed in the Cotton-Jordan brief,” they wrote in a brief. “Indeed, no one was physically hurt” as part of “any of those examples.”

“And none of those examples,” they added, “threatened something remotely as fundamental to our constitutional system as the peaceful transfer of executive power.”

Richard D. Bernstein, a lawyer for Mr. Luttig and other former officials who signed the supporting brief, said that allowing cases under the obstruction law to proceed was crucial.

“These obstruction prosecutions deter possible future invasions of Congress aimed at preventing the peaceful transfer of power,” he said.

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Another issue to watch is whether the court bites on the notion that there must some proof of evidence or document tampering to trigger the statute. If the justices accept that argument, it could mean that the law doesn’t really apply to boots-on-the-ground Jan. 6 rioters. But even if the court narrows the law in that way, it could still apply to Donald Trump’s Jan. 6-related criminal case.

Overall, the court seemed most accepting of arguments that pointed out the potential harms in interpreting the obstruction law at issue too broadly. The conservatives in particular seemed concerned that if the statute applied to Jan. 6 then it could be weaponized against a range of other political protests.

Arguments have concluded in the Jan. 6 case before the Supreme Court. Solicitor General Elizabeth Prelogar wrapped up her presentation to the justices, and Jeffrey Green, the lawyer for the Jan. 6 defendant, presented his rebuttal. The arguments were largely technical, focused on the interpretation of a statute that has mainly been construed to focus on the destruction of business records. The court’s decision in the case is expected to come by the end of the term in late June.

The court’s decision in today’s Jan. 6 case could eliminate some of the federal charges that former President Donald J. Trump is facing for his role in the plot to subvert the 2020 election. It could also jeopardize hundreds of Jan. 6 prosecutions.

Jeff Green seized on the concern by the conservative justices that an expansive view of the obstruction law could be a “weapon” against other political protest. “People are going to worry about the kinds of activity they engage in, even if it’s peaceful,” he says.

Justice Barrett asks Prelogar if the obstruction law would be triggered if someone merely stood outside the Capitol and urged the crowd on. Prelogar says if there was evidence that the person was, say, a ringleader of the crowd who made plans to help others to enter the building and stop the counting of electoral vote then, yes, they could be charged with obstruction. That pattern of facts tracks fairly closely to the case of Stewart Rhodes , the former leader of the Oath Keepers militia, who remained outside the Capitol on Jan. 6 but was charged with the obstruction count, among other crimes.

Prelogar says that even though the central figure in this case, Joseph Fischer, was charged with other crimes, including assaulting police officers, the obstruction count he faces was still valid. She says that the evidence in Fischer’s case shows he went to Capitol specifically to disrupt the election certification proceeding and so the obstruction count fits.

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Chief Justice Roberts asks Prelogar what constitutes formal acceptance of an Office of Legal Counsel memo as an official Justice Department position — rather than just being advice offered to the attorney general —and Prelogar says with a half laugh “I should probably know the answer to that one as a matter of D.O.J. policy.” Roberts says he should, too.

As someone who frequently sues the government seeking disclosures under the Freedom of Information Act, I can attest that the Justice Department often takes the position that Office of Legal Counsel opinions usually do not rise to the level of being a formally adopted policy. That means, in the government’s view, they are exempt from disclosure even though they are considered binding legal interpretations for the rest of the government.

Justice Barrett asks whether a defendant has to commit physical violence to fall under this statute. Prelogar says no. The fact that several Jan. 6 defendants who committed no violence but were still charged with this obstruction law has long been a complaint from rightwing critics of the Justice Department investigation of the Capitol attack.

If you’re just joining us now, the justices are hearing from Solicitor General Elizabeth Prelogar, who is arguing that a statute written to prohibit the destruction of business records should apply to Jan. 6 rioters. Several of the conservative justices, including Samuel A. Alito Jr. and Neil M. Gorsuch, have raised hypotheticals that appear to be pulled from recent headlines to ask whether other demonstrations, including a pro-Palestinian protest that blocks the Golden Gate Bridge, might trigger charges under the law.

Prelogar answers the question in part by noting that only 350 of the 1,350 or so people indicted in connection with Jan. 6 were charged with the obstruction count. Her point is that there are ways to use the statute narrowly. There has to be actual evidence that people not only committed obstruction but did so “corruptly,” as the law requires.

The implication of her argument is that the government has shown it has used the charge judiciously in Jan. 6 cases, so the interpretation she advocates won’t lead to a wholesale criminalization of political protest.

This line of argument about what kinds of political protest fall under this statute gets right to the heart of what, if anything, made Jan. 6 an unique moment in history. Some of the conservative justices are trying to tease out why Jan. 6 is covered by the statute and not, say, a pro-Palestinian protest on the Golden Gate Bridge or a protest at the court itself.

Prelogar is trying to fend off the notion that any political protest that disrupted an official proceeding could be criminalized by this law and punished by a maximum of 20 years in prison. She says that “a peaceful protest,” even one that was “quite disruptive” might not qualify for prosecution under this statute.

What does it mean to act ‘corruptly’?

The law that is the subject of Tuesday’s argument requires prosecutors to prove the defendant acted “corruptly.” But the meaning of that word is disputed.

Indeed, even the judges in the majority in a 2-to-1 appeals court ruling against Joseph W. Fischer, who is accused of violating the law by joining the mob that attacked the Capitol on Jan. 6, 2021, could not agree on just what the word meant.

In the lead opinion, Judge Florence Y. Pan wrote that Mr. Fischer’s conduct satisfied any plausible definition and that she would not choose among them. “I leave the exact contours of ‘corrupt’ intent for another day,” Judge Pan wrote.

But Judge Justin R. Walker said he was willing to concur in her opinion only on the condition that prosecutors be required to prove that Mr. Fischer had acted corruptly in the sense of having “an intent to procure an unlawful benefit either for himself or for some other person.”

Moreover, Judge Walker wrote, prosecutors must prove that “the defendant not only knew he was obtaining an ‘unlawful benefit’ but that his ‘objective’ or ‘purpose’ was to obtain that unlawful benefit.”

The definition was crucial, Judge Walker wrote, limiting what would otherwise be the law’s “breathtaking scope.”

“If I did not read ‘corruptly’ narrowly,” he wrote, “I would join the dissenting opinion.”

In dissent, Judge Gregory G. Katsas wrote that he would define “corruptly” even more narrowly, requiring an intent to procure “an unlawful financial, professional or exculpatory advantage.”

“In contrast, this case involves the much more diffuse, intangible benefit of having a preferred candidate remain president,” Judge Katsas wrote. “If that is good enough, then anyone acting to achieve a specific purpose would satisfy this requirement, for the purpose of the action would qualify as the benefit.”

Judge Walker said he was doubtful of that reading, but he added that Mr. Fischer’s conduct might qualify under even that strict standard.

“This case may involve a professional benefit,” he wrote. “The defendants’ conduct may have been an attempt to help Donald Trump unlawfully secure a professional advantage — the presidency.”

Solicitor General Elizabeth Prelogar presented the government’s argument that the statute should apply to the Jan. 6 defendants as “a straightforward question of statutory interpretation.” She says that, in plain English, the crime that day involved people attempting to obstruct the work of Congress.

Justice Clarence Thomas asks Solicitor General Elizabeth Prelogar if the government has applied this statute to other “violent protests” in the past.

Prelogar says no, but for the simple reason that an attack like the one that took place at the Capitol on Jan. 6 had never happened before.

If you're just joining us, the justices have been hearing argument from Jeffrey T. Green, a lawyer who represents Jan. 6 defendant, Joseph W. Fischer, a former Pennsylvania police officer. The argument thus far has been, as expected, technical and focused on interpretation of a decades-old statute focused on the destruction of business records.

Green just tried to argue that the left-wing attacks on the federal courthouse in Portland were analogous to the Jan. 6 attack on the Capitol. That argument was shut down by multiple federal judges in Washington who have been hearing Jan. 6 cases.

The argument here about whether interpreting the statute in a particular way would mean some of language is superfluous underscores a larger problem with the federal obstruction of justice statutes. Criminal law professors and practitioners agree that the statutes are a confusingly drafted, overlapping mess.

A key precedent ruled that a fish is not a tangible object.

In 2015, the Supreme Court limited the sweep of the statute at issue in Tuesday’s argument, the Sarbanes-Oxley Act of 2002.

The case involved fish. More precisely, undersized red grouper.

One of the sponsors of the law, Michael Oxley, filed a brief in that case explaining its history and purpose, saying it sought to close gaps that made it hard to prosecute accountants in the wake of the collapse of Enron, a giant energy company.

The law meant to address “specific loopholes” that Arthur Andersen, Enron’s accountants, “had exploited when they shredded business documents and destroyed hard drives in anticipation of federal law-enforcement action,” wrote Mr. Oxley, a former Ohio representative, who died in 2016 .

The law, Mr. Oxley wrote, was tightly focused on such conduct and should not be read too broadly. Though he did not address the provision at issue in the new case, it is a good bet that he would have been skeptical of prosecutors’ reliance on it in a case about an attack on the Capitol. (Paul S. Sarbanes, a former senator from Maryland and the law’s other principal sponsor, died in 2020 .)

The question for the justices in the old case, Yates v. United States , was broadly similar to the one the justices are considering on Tuesday: How far can a law meant to address white-collar business fraud be stretched to encompass other sorts of wrongful conduct?

The case arose from a 2007 search of the Miss Katie, a fishing vessel whose captain was John L. Yates. A field officer boarded the ship at sea and noticed fish that seemed less than 20 inches long, which was under the minimum legal size of red grouper at the time.

The officer measured the fish and placed the 72 he deemed too small in a crate. He issued a citation and instructed Mr. Yates to take the crate to port for seizure. But Mr. Yates had the fish thrown overboard and replaced with larger ones. A second inspection in port aroused suspicions, and a crew member eventually told law enforcement officials what had happened.

Mr. Yates was convicted of violating a part of the Sarbanes-Oxley Act that made it a crime to conceal or destroy “any record, document or tangible object with the intent to impede, obstruct or influence” a federal investigation. He was sentenced to 30 days’ imprisonment.

On appeal, Mr. Yates argued that the term “tangible object,” read in context, did not apply to fish. Mr. Oxley’s supporting brief agreed, saying Congress had meant to address the shredding of records and similar conduct.

“Against this unanimous evidence of congressional intent, the government’s reading of” the provision “to reach destruction of any and all things, including piscine creatures, falls flat,” Mr. Oxley wrote.

By a 5-to-4 vote, the Supreme Court ruled that the law did not reach fish.

“A fish is no doubt an object that is tangible,” Justice Ruth Bader Ginsburg wrote for four of the justices in the majority. But she added that it would cut the law “loose from its financial-fraud mooring to hold that it encompasses any and all objects, whatever their size or significance, destroyed with obstructive intent.”

In dissent, Justice Elena Kagan wrote that the plain words of the law mattered more than its purpose. “A fish is, of course, a discrete thing that possesses physical form,” Justice Kagan wrote, citing as authority the Dr. Seuss classic “One Fish, Two Fish Red Fish Blue Fish.”

Defense lawyers have long argued that there was no document tampering aspect at all in the storming of the Capitol and one federal judge in Washington agreed with them, which is essentially why we’re here in the Supreme Court today. But it is possible to argue, as the special counsel Jack Smith has done in Trump’s case, that there was document tampering on Jan. 6. That’s because the certification proceeding involved so-called fake slates of electors wrongly claiming that Trump won the election in several states won by President Biden.

The dense semantics being argued here are circling an important question: whether this statute — designed to curb things like destroying documents — requires specific proof that records were actually tampered with. And further: whether document tampering has anything to do with pro-Trump rioters breaking into the Capitol on Jan. 6, 2021.

A key question in the case: the meaning of ‘otherwise’

The provision at issue in the case, from the Sarbanes-Oxley Act of 2002, has two parts. The question for the justices is how they interact. And that depends on the word that links them: “otherwise.”

The first part of the provision focuses on evidence, saying that anyone who corruptly “alters, destroys, mutilates or conceals a record, document or other object” to affect an official proceeding is guilty of a felony.

So far, so good. It is uncontroversial to reinforce that destroying documents to impede an investigation has been a core purpose of the law, which was prompted by the shredding of documents in an accounting scandal.

The second part of the provision makes it a crime “otherwise” to corruptly obstruct, influence or impede any official proceeding. Prosecutors say the defendant in the case, Joseph W. Fischer, did that by joining the mob that attacked the Capitol on Jan. 6, 2021.

The heart of the case is how the first part of the provision pivots to the second part.

The ordinary meaning of “otherwise,” prosecutors say, is “in a different manner.” That means, they say, that the obstruction of official proceedings need not involve the destruction of evidence. The second part, they say, is a broad catchall for any kind of corrupt interference with an official proceeding.

Lawyers for Mr. Fischer, the defendant in Tuesday’s case, counter that the first part must inform and limit the second one — meaning that the obstruction of official proceedings must be linked to the destruction of evidence. They would read “otherwise” as “similarly.”

The alternative, they say, would be to create a crime of breathtaking scope that would allow prosecutors to charge political protesters and others with felonies carrying 20-year prison sentences.

In 2008, in Begay v. United States , the court considered a law with a broadly similar structure, the Armed Career Criminal Act , which requires mandatory sentences for people convicted of possessing firearms if they have earlier been found guilty of three violent felonies. In one clause, it listed specific crimes that qualified as violent felonies — including burglary, arson and extortion.

Then, as in the new case, there followed an “otherwise” clause, this one adding any crime that “otherwise involves conduct that presents a serious potential risk of physical injury to another.”

The Supreme Court ruled that the examples informed and limited the sweep of the “otherwise” clause. If Congress had “meant the statute to be all-encompassing, it is hard to see why it would have needed to include the examples at all,” Justice Stephen G. Breyer wrote for the majority.

A drunken driving offense, the court ruled, did not qualify as one of the covered crimes even though the plain words of the clause would seem to encompass it.

Mr. Fisher’s lawyers say that the “otherwise” clause in the obstruction statute must also be anchored in the preceding clause.

The U.S. Court of Appeals for the District of Columbia Circuit disagreed, with Judge Florence Y. Pan writing that the two uses of “otherwise” were different. The gun law, she wrote, “includes a list of examples followed by ‘otherwise’ in a single, unbroken sentence.”

By contrast, she wrote, the “otherwise” in the Sarbanes-Oxley Act “sits within a separately numbered subparagraph, after a semicolon and line break, all of which put distance between it and the lists of verbs and objects” in the previous part.

In dissent, Judge Gregory G. Katsas wrote that “the relationship created by the word otherwise does not depend on punctuation or line breaks.”

Rather, he wrote, “it flows from the connotation of similarity,” among other factors. That meant, he concluded, that the second part of the provision applies “only to acts that affect the integrity or availability of evidence.”

What does the law at issue in the case actually say?

At its core, the case is about the meaning of a provision of the Sarbanes-Oxley Act of 2002. It was enacted following the collapse of Enron, a giant energy company, after the exposure of widespread accounting fraud and the destruction of documents by the company’s outside auditor.

There is an uneasy fit between the immediate purpose of the law and its recent use in more than 300 prosecutions arising from the violent riot that forced a halt to the constitutionally required congressional count of presidential electors’ ballots.

At least part of what it meant to accomplish was to address a gap in the federal criminal code at the time: It was a crime to persuade others to destroy records relevant to an investigation or official proceeding but not to do so oneself.

The law meant to close that gap. It did, in a two-part provision, Section 1512(c) of the federal criminal code:

(c) Whoever corruptly — (1) alters, destroys, mutilates, or conceals a record, document, or other object , or attempts to do so, with the intent to impair the object’s integrity or availability for use in an official proceeding or (2) otherwise obstructs, influences, or impedes any official proceeding , or attempts to do so, shall be fined under this title or imprisoned not more than 20 years, or both.

The first part focuses on evidence, making it a felony to tamper with it to affect an official proceeding. The second part makes it a crime “otherwise” to corruptly obstruct, influence or impede any official proceeding.

The heart of this case is the pivot from the first part to the second part. The ordinary meaning of “otherwise,” prosecutors say, is “in a different manner.” That means, they say, that the obstruction of official proceedings need not involve the destruction of evidence — in their view, making the second part a broad catchall for any kind of corrupt interference with an official proceeding.

The lawyers for Joseph W. Fischer, who was accused of breaching the Capitol on Jan. 6, 2021, and of assaulting police officers, counter that the first part must inform and limit the second one — meaning that the obstruction of official proceedings must be linked to the destruction of evidence. They would read “otherwise” as “similarly.”

The alternative, they say, would be to create a felony of breathtaking scope that would allow prosecutors to charge political protesters with felonies carrying 20-year prison sentences.

The court’s decision could have a direct impact on Donald Trump.

While the Supreme Court’s hearing is intended to determine the scope and validity of an obstruction law used against hundreds of rioters who broke into the Capitol on Jan. 6, any decision could also have an impact on a separate criminal case: one in which former President Donald J. Trump has been accused of plotting to overturn the 2020 election.

Two of the four criminal counts Mr. Trump is facing in that case are based on the obstruction law. In an indictment filed in Washington last summer, he was charged with conspiring to obstruct the certification of the election on Jan. 6 during a joint session of Congress at the Capitol as well as with actually obstructing it.

If the justices determine that prosecutors improperly used the obstruction law against members of the pro-Trump mob who disrupted the session, Mr. Trump’s lawyers will surely seek to have the charges against him dismissed as well. In fact, they already tried that in October. They argued unsuccessfully to the trial judge in the case that Mr. Trump’s indictment unfairly used the statute, which was initially “directed at the destruction of records in accounting fraud,” by applying it “to disputing the outcome of a presidential election.”

“This stretches the statutory language beyond any plausible mooring to its text,” the lawyers wrote.

Jack Smith, the special counsel handling Mr. Trump’s case, has told the Supreme Court that the two obstruction counts against the former president would be still valid even if the justices narrowed the law to cover only crimes that involved tampering with documents or records.

Mr. Trump triggered that provision of the law, Mr. Smith has said, by plotting to create fake slates of electors that claimed he won in several keys swing states that he actually lost to President Biden. Mr. Smith has accused Mr. Trump of trying to use those fake slates to throw the certification proceeding into chaos and by urging his vice president, Mike Pence, to capitalize on the confusion by single-handedly declaring him the winner of the race.

Even if the obstruction count were ultimately removed from Trump’s indictment, it would probably not be a fatal blow.

The indictment contains two other conspiracy counts that overlap almost entirely with the accusations in the obstruction counts. One of the conspiracy charges accuses Mr. Trump of committing fraud by using deceit to subvert the normal course of the election. The other charges him with plotting to deprive millions of Americans of the right to have votes properly counted.

Prosecutions tied to the Capitol attack have ensnared more than 1,380 people.

The investigation of the Jan. 6, 2021, Capitol attack is already the largest criminal inquiry in Justice Department history, federal prosecutors have said. And even after more than three years, it has shown little sign of slowing down.

Every week, a few more rioters are arrested and charges against them are unsealed in Federal District Court in Washington. Prosecutors have suggested that a total of 2,000 or 2,500 people could ultimately face indictment for their roles in the attack.

More than 1,380 people had been charged in connection with the attack as of early this month, according to the Justice Department. Among the most common charges brought against them are two misdemeanors: illegal parading inside the Capitol and entering and remaining in a restricted federal area, a type of trespassing.

About 350 rioters have been accused of violating the obstruction statute that the Supreme Court is considering at its hearing, and nearly 500 people have been charged with assaulting police officers. Many rioters have been charged with multiple crimes, the most serious of which so far has been seditious conspiracy.

Almost 800 defendants have already pleaded guilty; about 250 of them have done so to felony charges. Prosecutors have won the vast majority of the cases that have gone to trial: More than 150 defendants have been convicted at trial and only two have been fully acquitted.

More than 850 people have been sentenced so far, and about 520 have received at least some time in prison. The stiffest penalties have been handed down to the former leaders of the Proud Boys and Oath Keepers, far-right extremist groups that played central roles in the Capitol attack.

Enrique Tarrio, the former Proud Boys leader, was sentenced to 22 years in prison , and Stewart Rhodes, who once led the Oath Keepers, was given an 18-year term .

The prosecution of a police officer, Joseph Fischer, led to this hearing.

The man whose case led to the Supreme Court hearing on a controversial federal obstruction law is a former police officer from rural Pennsylvania indicted on charges of storming the Capitol on Jan. 6, 2021, and crashing into a line of his fellow officers defending the building.

Joseph W. Fischer was working for the police department in North Cornwall Township, Pa., when prosecutors say he pushed his way into the Capitol while holding up his cellphone to take videos of the surge. Once inside, he and another rioter “galloped forward,” prosecutors say, making contact with a line of officers who were fighting off the crowd.

Mr. Fischer fell to the ground and, as some nearby officers helped him to his feet, he tried to engage with them, prosecutors say.

“I’m a cop too,” he said, “sometimes the country is worth more than your job.”

According to court papers, Mr. Fischer was concerned about his own job before making the trip to Washington. Investigators unearthed text messages he wrote to the chief of his department, saying that things could get “violent” on Jan. 6 and that the crowd should “storm the capital and drag all the democrates.”

He also warned the chief that he might need him to post his bail, the papers said.

Township officials suspended Mr. Fischer without pay on the day of his arrest in February 2021 and later fired him. But he has pushed back against the government’s description of behavior on Jan. 6.

His lawyers say that he and a companion were prepared to leave Washington that day after listening President Trump’s speech near the White House and turned around to head toward the Capitol only after hearing about the mounting protest there. The lawyers also claim that Mr. Fischer arrived at the Capitol grounds well after Congress had recessed the proceeding to certify the results of the 2020 election because of the attack.

“As Mr. Fischer walked toward the east side of the building, no barricades or fences impeded him,” the lawyers wrote in their brief to the Supreme Court.

Mr. Fischer has disputed the assertion by prosecutors that he charged the police line inside the Capitol, telling the court instead that he was pushed into the officers by “the weight of the crowd.”

He also characterized his interactions with the officers differently than prosecutors did, claiming that he merely talked with one of the officers and patted him on the shoulder.

An accounting scandal spurred the law used to prosecute Jan. 6 defendants.

The provision at issue in the case is part of the Sarbanes-Oxley Act, a 2002 law enacted after the collapse of Enron, a giant energy company, after the exposure of widespread accounting fraud and the destruction of documents by its outside auditor, Arthur Andersen.

The Supreme Court has said that the purpose of the law was “to safeguard investors in public companies and restore trust in the financial markets following the collapse of Enron.”

At least part of what the law meant to accomplish was to address a gap in the federal criminal code: it was a crime to persuade others to destroy records relevant to an investigation or official proceeding but not to do so oneself. The Sarbanes-Oxley Act was meant to close that gap.

Lawyers for Joseph W. Fischer, charged under the law with obstructing an official proceeding by joining the mob that stormed the Capitol on Jan. 6, 2021, said his case had an Alice-in-Wonderland quality.

“The Through the Looking Glass moment here,” they wrote in a Supreme Court brief , “would be for those who wrote the Sarbanes-Oxley Act upon learning that they had created a new and breathtaking obstruction offense by endeavoring to close the narrow Enron-Arthur Anderson loophole.”

Indeed, in a different case on the scope of the statute, one of the sponsors of the law, Michael Oxley, filed a supporting brief saying prosecutors had interpreted it too broadly. The law meant to address “specific loopholes” that Arthur Andersen “had exploited when they shredded business documents and destroyed hard drives in anticipation of federal law-enforcement action,” wrote Mr. Oxley, a former Ohio representative who died in 2016 .

In that case, concerning a separate provision of the law, Justice Ruth Bader Ginsburg said the law’s origins informed its meaning and spared the defendant.

“The Sarbanes-Oxley Act, all agree, was prompted by the exposure of Enron’s massive accounting fraud and revelations that the company’s outside auditor, Arthur Andersen, had systematically destroyed potentially incriminating documents,” she wrote for four of the justices in the majority. She added that the government had acknowledged that the provision “was intended to prohibit, in particular, corporate document-shredding to hide evidence of financial wrongdoing.”

An earlier version of this article misstated the year of the Jan. 6 attack on the Capitol. It was 2021, not 2001.

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Supreme Court Appears Skeptical of Using Obstruction Law to Charge Jan. 6 Rioters

The Supreme Court seemed wary on Tuesday of letting prosecutors use a federal obstruction law to charge hundreds of rioters involved in the Capitol attack on Jan. 6, 2021.

A decision rejecting the government’s interpretation of the law could not only disrupt those prosecutions but also eliminate half of the charges against former President Donald J. Trump in the federal case accusing him of plotting to subvert the 2020 election.

Mr. Trump’s case did not come up at the argument, which was largely focused on trying to make sense of a statute, enacted to address white-collar crime, that all concerned agreed was not a model of clarity. But the justices’ questions also considered the gravity of the assault and whether prosecutors have been stretching the law to reach members of the mob responsible for the attack, which interrupted certification of Joseph R. Biden Jr.’s electoral victory.

Justice Clarence Thomas, who returned to the bench after an unexplained absence on Monday, asked whether the government was engaging in a kind of selective prosecution. “There have been many violent protests that have interfered with proceedings,” he said. “Has the government applied this provision to other protests?”

Justice Sonia Sotomayor took a different view of what happened on Jan. 6. “We’ve never had a situation before where there’s been a situation like this with people attempting to stop a proceeding violently,” she said.

The question for the justices was whether one of the laws used to prosecute some of the members of the mob that stormed the Capitol fits their conduct. The law, a provision of the Sarbanes-Oxley Act of 2002, contains a broad catchall provision that makes it a crime to corruptly obstruct, influence or impede any official proceeding.

But the provision is linked to a previous one aimed at altering evidence. Chief Justice John G. Roberts Jr. said the catchall provision must be read in context. Since the Jan. 6 defendants were not accused of altering evidence, he said, the catchall provision did not apply.

Other members of the court’s conservative majority said that reading the catchall provision in isolation would allow prosecutions of all sorts of protesters.

Two members of the court’s liberal wing responded that the catchall provision was broad by design and not tethered to the previous clause. Congress had meant, they said, to give prosecutors tools to address situations that the lawmakers could not anticipate.

The effect of a ruling rejecting the use of the provision to prosecute Jan. 6 defendants is not completely clear. Most such defendants have not been charged under the provision, which prosecutors have reserved for the most serious cases, and those who have been charged under it face other counts as well.

The defendant in Tuesday’s case, Joseph W. Fischer, for instance, faces six other charges.

Nor is it clear that a ruling in Mr. Fischer’s favor would erase any charges against Mr. Trump under the law. Jack Smith, the special counsel overseeing the federal election interference case against the former president, has said Mr. Trump’s conduct could be considered a crime under even a narrow reading of the 2002 law.

Whatever the larger consequences of the court’s ruling, expected by late June, several justices on Tuesday seemed troubled by the government’s interpretation of the law, saying it would allow many other kinds of prosecutions.

“Would a sit-in that disrupts a trial or access to a federal courthouse qualify?” Justice Neil M. Gorsuch asked. “Would a heckler in today’s audience qualify, or at the State of the Union address? Would pulling a fire alarm before a vote qualify for 20 years in federal prison?”

Justice Samuel A. Alito Jr. allowed that “what happened on Jan. 6 was very, very serious.” But he added that the prosecutors’ theory could reach, say, protests in the Supreme Court’s courtroom, which have occurred from time to time.

Elizabeth B. Prelogar, the U.S. solicitor general, began her argument by recalling the events of Jan. 6, saying that what some of the participants did that day amounted to obstruction covered by the law.

“On Jan. 6, 2021, a violent mob stormed the United States Capitol and disrupted the peaceful transition of power,” she said. “Many crimes occurred that day, but in plain English, the fundamental wrong committed by many of the rioters, including petitioner, was a deliberate attempt to stop the joint session of Congress from certifying the results of the election. That is, they obstructed Congress’s work in that official proceeding.”

Justice Amy Coney Barrett asked how to distinguish the attack on the Capitol from other actions that have disrupted official proceedings. “Tell me why I shouldn’t be concerned about the breadth of the government’s reading?” she asked.

The law at issue in the case was enacted in the wake of the collapse of the energy giant Enron.

Mr. Fischer, a former police officer, was charged with violating it and with six other crimes. Justice Brett M. Kavanaugh asked why the other charges were insufficient.

“Why aren’t those six counts good enough just from the Justice Department’s perspective given that they don’t have any of the hurdles?” he asked.

Ms. Prelogar responded that the other counts did not fully reflect Mr. Fischer’s culpability.

The law was prompted by accounting fraud and the destruction of documents, but the provision is written in broad terms.

At least part of what the law meant to accomplish was to address a gap in the federal criminal code: It was a crime to persuade others to destroy records relevant to an investigation or official proceeding but not to do so oneself. The law sought to close that gap.

It did that in a two-part provision. The first part makes it a crime to corruptly alter, destroy or conceal evidence to frustrate official proceedings. The second part, at issue in Mr. Fischer’s case, makes it a crime “otherwise” to corruptly obstruct, influence or impede any official proceeding.

The heart of the case is at the pivot from the first part to the second. The ordinary meaning of “otherwise,” prosecutors say, is “in a different manner.” That means, they say, that the obstruction of official proceedings need not involve the destruction of evidence. The second part, they say, is broad catchall applying to all sorts of conduct.

Justice Elena Kagan said the catchall provision was a purposefully broad reaction to the Enron debacle.

“What Enron convinced them of was that there were gaps in these statutes,” she said of the lawmakers who enacted it.

She added: “But they didn’t know exactly what those gaps were. So they said, let’s have a backstop provision. And this is their backstop provision.”

Justice Sotomayor agreed. “They wanted to cover every base, and they didn’t do it in a logical way, but they managed to cover every base,” she said.

Jeffrey T. Green, a lawyer for Mr. Fischer, said the court should not interpret the 2002 law to create a crime of breathtaking scope that would allow prosecutors to charge political protesters and others with felonies carrying 20-year prison sentences.

He said that the first part of the provision must inform and limit the second one — to obstruction linked to the destruction of evidence. They would read “otherwise,” in other words, as “similarly.”

Chief Justice John G. Roberts Jr., citing a unanimous opinion he wrote last week, appeared to agree. “The general phrase,” he said, “is controlled and defined by reference to the terms that precede it,” he said. “The ‘otherwise’ phrase is more general, and the terms that precede it are ‘alters, destroys, mutilates, or conceals a record or document.’”

The case is one of several on the court’s docket this term affecting or involving Mr. Trump. In a separate case to be argued next week, the justices will consider Mr. Trump’s claim that he is totally immune from prosecution.

Mr. Fischer is accused of entering the Capitol around 3:24 p.m. on Jan. 6, with the counting of electoral ballots having been suspended after the initial assault.

He had told a superior in a text message, prosecutors said, that “it might get violent.” In another, he wrote that “they should storm the capital and drag all the democrates into the street and have a mob trial.”

Prosecutors say that videos showed Mr. Fischer yelling “Charge!” before pushing through the crowd, using a vulgar term to berate police officers and crashing into a line of them.

Mr. Fischer’s lawyers dispute some of this. But the question for the justices is legal, not factual: Does the 2002 law cover what Mr. Fischer is accused of?

As the end of the argument neared, Justice Ketanji Brown Jackson, a liberal, indicated that she had reservations about the government’s position, saying that the court should not lose sight of “the backdrop of a real-world context.”

“It was in the wake of Enron,” she said. “There was document destruction, and, you know, there was nothing as far as I can tell in the enactment history as it was recorded that suggests that Congress was thinking about obstruction more generally.”

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Gender pay gap in U.S. hasn’t changed much in two decades

The gender gap in pay has remained relatively stable in the United States over the past 20 years or so. In 2022, women earned an average of 82% of what men earned, according to a new Pew Research Center analysis of median hourly earnings of both full- and part-time workers. These results are similar to where the pay gap stood in 2002, when women earned 80% as much as men.

As has long been the case, the wage gap is smaller for workers ages 25 to 34 than for all workers 16 and older. In 2022, women ages 25 to 34 earned an average of 92 cents for every dollar earned by a man in the same age group – an 8-cent gap. By comparison, the gender pay gap among workers of all ages that year was 18 cents.

While the gender pay gap has not changed much in the last two decades, it has narrowed considerably when looking at the longer term, both among all workers ages 16 and older and among those ages 25 to 34. The estimated 18-cent gender pay gap among all workers in 2022 was down from 35 cents in 1982. And the 8-cent gap among workers ages 25 to 34 in 2022 was down from a 26-cent gap four decades earlier.

The gender pay gap measures the difference in median hourly earnings between men and women who work full or part time in the United States. Pew Research Center’s estimate of the pay gap is based on an analysis of Current Population Survey (CPS) monthly outgoing rotation group files ( IPUMS ) from January 1982 to December 2022, combined to create annual files. To understand how we calculate the gender pay gap, read our 2013 post, “How Pew Research Center measured the gender pay gap.”

The COVID-19 outbreak affected data collection efforts by the U.S. government in its surveys, especially in 2020 and 2021, limiting in-person data collection and affecting response rates. It is possible that some measures of economic outcomes and how they vary across demographic groups are affected by these changes in data collection.

In addition to findings about the gender wage gap, this analysis includes information from a Pew Research Center survey about the perceived reasons for the pay gap, as well as the pressures and career goals of U.S. men and women. The survey was conducted among 5,098 adults and includes a subset of questions asked only for 2,048 adults who are employed part time or full time, from Oct. 10-16, 2022. Everyone who took part is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way nearly all U.S. adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories. Read more about the ATP’s methodology .

Here are the questions used in this analysis, along with responses, and its methodology .

The  U.S. Census Bureau has also analyzed the gender pay gap, though its analysis looks only at full-time workers (as opposed to full- and part-time workers). In 2021, full-time, year-round working women earned 84% of what their male counterparts earned, on average, according to the Census Bureau’s most recent analysis.

Much of the gender pay gap has been explained by measurable factors such as educational attainment, occupational segregation and work experience. The narrowing of the gap over the long term is attributable in large part to gains women have made in each of these dimensions.

Related: The Enduring Grip of the Gender Pay Gap

Even though women have increased their presence in higher-paying jobs traditionally dominated by men, such as professional and managerial positions, women as a whole continue to be overrepresented in lower-paying occupations relative to their share of the workforce. This may contribute to gender differences in pay.

Other factors that are difficult to measure, including gender discrimination, may also contribute to the ongoing wage discrepancy.

Perceived reasons for the gender wage gap

When asked about the factors that may play a role in the gender wage gap, half of U.S. adults point to women being treated differently by employers as a major reason, according to a Pew Research Center survey conducted in October 2022. Smaller shares point to women making different choices about how to balance work and family (42%) and working in jobs that pay less (34%).

There are some notable differences between men and women in views of what’s behind the gender wage gap. Women are much more likely than men (61% vs. 37%) to say a major reason for the gap is that employers treat women differently. And while 45% of women say a major factor is that women make different choices about how to balance work and family, men are slightly less likely to hold that view (40% say this).

Parents with children younger than 18 in the household are more likely than those who don’t have young kids at home (48% vs. 40%) to say a major reason for the pay gap is the choices that women make about how to balance family and work. On this question, differences by parental status are evident among both men and women.

Views about reasons for the gender wage gap also differ by party. About two-thirds of Democrats and Democratic-leaning independents (68%) say a major factor behind wage differences is that employers treat women differently, but far fewer Republicans and Republican leaners (30%) say the same. Conversely, Republicans are more likely than Democrats to say women’s choices about how to balance family and work (50% vs. 36%) and their tendency to work in jobs that pay less (39% vs. 30%) are major reasons why women earn less than men.

Democratic and Republican women are more likely than their male counterparts in the same party to say a major reason for the gender wage gap is that employers treat women differently. About three-quarters of Democratic women (76%) say this, compared with 59% of Democratic men. And while 43% of Republican women say unequal treatment by employers is a major reason for the gender wage gap, just 18% of GOP men share that view.

Pressures facing working women and men

Family caregiving responsibilities bring different pressures for working women and men, and research has shown that being a mother can reduce women’s earnings , while fatherhood can increase men’s earnings .

Employed women and men are about equally likely to say they feel a great deal of pressure to support their family financially and to be successful in their jobs and careers, according to the Center’s October survey. But women, and particularly working mothers, are more likely than men to say they feel a great deal of pressure to focus on responsibilities at home.

About half of employed women (48%) report feeling a great deal of pressure to focus on their responsibilities at home, compared with 35% of employed men. Among working mothers with children younger than 18 in the household, two-thirds (67%) say the same, compared with 45% of working dads.

When it comes to supporting their family financially, similar shares of working moms and dads (57% vs. 62%) report they feel a great deal of pressure, but this is driven mainly by the large share of unmarried working mothers who say they feel a great deal of pressure in this regard (77%). Among those who are married, working dads are far more likely than working moms (60% vs. 43%) to say they feel a great deal of pressure to support their family financially. (There were not enough unmarried working fathers in the sample to analyze separately.)

About four-in-ten working parents say they feel a great deal of pressure to be successful at their job or career. These findings don’t differ by gender.

Gender differences in job roles, aspirations

Overall, a quarter of employed U.S. adults say they are currently the boss or one of the top managers where they work, according to the Center’s survey. Another 33% say they are not currently the boss but would like to be in the future, while 41% are not and do not aspire to be the boss or one of the top managers.

Men are more likely than women to be a boss or a top manager where they work (28% vs. 21%). This is especially the case among employed fathers, 35% of whom say they are the boss or one of the top managers where they work. (The varying attitudes between fathers and men without children at least partly reflect differences in marital status and educational attainment between the two groups.)

In addition to being less likely than men to say they are currently the boss or a top manager at work, women are also more likely to say they wouldn’t want to be in this type of position in the future. More than four-in-ten employed women (46%) say this, compared with 37% of men. Similar shares of men (35%) and women (31%) say they are not currently the boss but would like to be one day. These patterns are similar among parents.

Note: This is an update of a post originally published on March 22, 2019. Anna Brown and former Pew Research Center writer/editor Amanda Barroso contributed to an earlier version of this analysis. Here are the questions used in this analysis, along with responses, and its methodology .

What is the gender wage gap in your metropolitan area? Find out with our pay gap calculator

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