Single-Case Research

Single-Case Design Logic

As mentioned, SCRDs are highly flexible experimental designs enabling one to determine “what works” when supporting an individual student, a group of students, or a school. SCRDs grew out of the field of applied behavior analysis, which involves the application of key behavioral principles (e.g., positive reinforcement) to applied contexts. The methodological logic includes four key components.

First, SCRD involves within-subject design whereby each participant serves as their own control. This is very different from group design methodology, which involves between-groups comparisons. For example, in traditional group designs, students with similar concerns (e.g., high levels of internalizing behaviors) are detected using consistent procedures (e.g., data from systematic screeners) and randomly assigned (such that each person as an equal and independent opportunity to be assigned to established conditions) to either an experimental (e.g., cognitive restructuring) or control (e.g., business as usual) condition. Using this methodology, students are often pretested on measures of interest (e.g., participation in class discussions) before the intervention begins (pretest) and again after the intervention concludes (posttest and later maintenance). In group designs, the intervention condition is fixed—the intervention does not change, participants in the control group do not access the intervention, and integrity data are collected to make sure there is no contamination between conditions. Then, analyses are conducted to determine how performance shifts over time for students who did (experimental condition) and did not (control condition) receive the intervention being tested. In SCRD, each student receives the intervention following a baseline condition. Using frequent, repeated assessment of student performance during baseline and then intervention conditions (rather than pre-/post intervention assessments), comparisons are made to see how each students’ performance shifts following systematic introduction of the intervention (e.g., cognitive restructuring) on the performance measures of interest (e.g., participation). These are within-subject comparisons.

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