Education Single-Subject Research Design
Timothy J. Lewis, Nicholas Gage
  • LAST REVIEWED: 19 November 2019
  • LAST MODIFIED: 25 June 2013
  • DOI: 10.1093/obo/9780199756810-0103


Single-subject research, at times referred to as single-case research, is a quantitative approach to examine functional relationships between baseline and experimental conditions over time within individual subjects. The central features of single-subject research include collecting repeated measures of behavior through direct observation across several sessions, comparing rates or amount of behavior between baseline or typical conditions to an intervention condition, and repeating baseline and intervention phases to note a functional relationship between the introduction and withdrawal of the intervention or independent variable (IV) and the subject’s behavior or dependent variable (DV). Collected observational data are converted to a standard metric and plotted in a line graph and visually analyzed to note variations in trend, level, and variability of the data across baseline and intervention conditions.

General Overviews

First described by Murray Sidman in 1960 (Sidman 1960) to study behavioral principles within psychology and then later expanded to become a central element of applied behavior analysis (Baer, et al. 1968; Baer, et al. 1987; Cooper, et al. 2007), single-subject research is used across several disciplines including special and general education, social work, communication sciences, and rehabilitative therapies. Horner and colleagues report that more than forty-five scholarly journals accept and publish single-subject research studies (Horner, et al. 2005). See also Campbell and Stanley 1963, Kazdin and Tuma 1982, and Kratochwill and Levin 1992.

  • Baer, Donald M., Montrose M. Wolf, and Todd R. Risley. 1968. Some current dimensions of applied behavior analysis. Journal of Applied Behavior Analysis 1.1: 91–97.

    DOI: 10.1901/jaba.1968.1-91

    A seminal article in the field of applied behavior analysis, this article operationally defines the essential features of applied behavior analysis and the experimental conditions under which applied behavior analysis principles can and should be studied.

  • Baer, Donald M., Montrose M. Wolf, and Todd R. Risley. 1987. Some still-current dimensions of applied behavior analysis. Journal of Applied Behavior Analysis 20.4: 313–327.

    DOI: 10.1901/jaba.1987.20-313

    A follow-up to the seminal Baer, et al. 1968, this article provides the foundation for the applied behavior analysis field by outlining the general premise of applied behavior analytic research, which is the foundation of single-subject designs. The paper articulates that analysis of an effect in behavior analytic research, particularly single-subject research, should focus on practical significance that can be observed.

  • Campbell, Donald T., and Julian C. Stanley. 1963. Experimental and quasi-experimental designs for research. Boston: Houghton Mifflin.

    A seminal text on conducting behavioral research, Campbell and Stanley provide a chapter on single-subject designs and the framework for what has become the standard in threats to internal and external validity and how each design accounts for these.

  • Cooper, John O., Timothy E. Heron, and William L. Heward. 2007. Applied behavior analysis. 2d ed. Upper Saddle River, NJ: Pearson/Merrill-Prentice Hall.

    This textbook provides an overview of single-subject research designs and, importantly, details how to assess behavior change using visual analysis in clinical/applied and research contexts within an applied behavior analysis context.

  • Horner, Robert H., Edward G. Carr, James Halle, Gail McGee, Samuel Odom, and Mark Wolery. 2005. The use of single-subject research to identify evidence-based practices in special education. Exceptional Children 71.2: 165–179.

    This article outlines the essential features within and across single-subject research studies to ascertain a minimal level of evidence to brand the practice under investigation “evidence-based.”

  • Kazdin, Alan E., and A. Hussain Tuma, eds. 1982. Single-case research designs. New Directions for Methodology of Behavioral Science 13. San Francisco: Jossey-Bass.

    This edited text provides a rationale and the basic logic of single-subject research within the context of traditional psychological and clinical research. Although dated with respect to current issues and design variations, the text provides an historical context and establishes the roots of single-subject research.

  • Kratochwill, Thomas R., and Joel R. Levin, eds. 1992. Single-case research design and analysis: New directions for psychology and education. Hillsdale, NJ: Lawrence Erlbaum.

    This text provides a series of chapters setting the stage for contemporary issues related to single-subject research including limitations of visual analysis, effect size, statistical analysis, and the appropriateness of meta-analyses across single-subject research. The book ends with a chapter on the current state of the art at the time and recommended future directions.

  • Sidman, Murray. 1960. Tactics of scientific research: Evaluating experimental data in psychology. New York: Basic Books.

    A seminal text that laid the foundation for single-subject research within behavioral psychology.

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