Academic journal article Education & Treatment of Children

Considerations for the Systematic Analysis and Use of Single-Case Research

Academic journal article Education & Treatment of Children

Considerations for the Systematic Analysis and Use of Single-Case Research

Article excerpt


Single-case research designs provide a rigorous research methodology for documenting experimental control. If single-case methods are to gain wider application, however, a need exists to define more clearly (a) the logic of single-case designs, (b) the process and decision rules for visual analysis, and (c) an accepted process for integrating visual analysis and statistical analysis. Considerations for meeting these three needs are discussed.

Single-case research methods provide a scientifically rigorous approach for documenting experimental control (internal validity) and advancing effective practices in education, behavior analysis and psychology (Hersen & Barlow, 1976; Kazdin, 1982; Kennedy, 2005; Kratochwill, 1978; Kratochwill & Levin, 1992; McReynolds & Kearns, 1983; Richards, Taylor, Ramasamy & Richards, 1999; Tawney & Gast, 1984; Todman & Dugard, 2001). The long history of conceptual and clinical contributions from single-case research is encouraging (e.g., Dunlap & Kern, 1997; Odom & Strain, 2002; Sidman, 1960; Wolery & Dunlap, 2001) but underutilized as we consider the standards by which a new model for educational science is being defined (Kratochwill & Stoiber, 2000; Odom et al., 2005; Whitehurst, 2003). If findings from single-case research are to reach the larger scientific and clinical community, however, a more transparent process is needed for (a) defining the logic guiding single-case methods, (b) describing the decision-rules guiding visual analysis of single-case data, (c) defining professional standards for using single-case research to identify empirically supported interventions, and (d) extending analysis of single-case results to include both visual and statistical methods.

We begin by revisiting the rationale for considering the addition of statistical analysis to the standard visual analysis protocols for single-case results. We place this discussion in the context of three emerging standards for assessing any research report. We then summarize decision-rules that may help standardize visual analysis. Finally, we extend the logic from these rules to considerations that might guide the development and use of formal effect-size indices.

A Rationale for Re-considering Statistical Analysis of Single-case Research

Statistical analysis of single-case data has been proposed to both define the statistical significance of observed effects, and document the effect size in a manner that facilitates meta-analyses. To date, however, no statistical approach for examining single-case research has met three fundamental criteria: (a) controls for auto-correlation (e.g. the fact that scores are not independent), (b) provides a metric that integrates the full constellation of variables used in visual analysis of single-case designs to assess the level of experimental control demonstrated by the data, and (c) produces an effect-size measure for the whole study (as opposed to two adjacent phases). Different proposals have succeeded in elements of this task (Busk & Serlin, 1992; Parker & Hagan-Burke, 2007; Parker, Hagan-Burke & Vannest, 2007), but none has offered a model that meets all three criteria. A full review of the history, considerations, and frustrations with the application of statistical analysis to single-case research is under development by two research projects funded by the U.S. Department of Education's Institute of Educational Sciences.

We argue that two emerging trends in the field make the need to reconsider statistical analysis of single-case data particularly important. The first is a new model for educational research that is based on high experimental rigor with emphasis on meta-analysis. With the founding of the Institute of Education Sciences (U.S. Department of Education, Education Science Reform Act, 2002), the U.S. Department of Education has launched a major initiative focused on guiding educational innovation based on scientific findings and ensuring that research in education meets the highest standards of science. …

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