Classroom-Based Applications of Single-Case Designs:

Methodological and Statistical Issues

Joel R. Levin

University of Arizona

Methodological Standards for Methodological Standards for Single-Case ResearchSingle-Case Research

Separate credibility standards should be applied for each type of intervention research, conventional group and single-case

– Guidelines are now in effect for conventional group RCTs (Moher, Schulz, & Altman (2001)

– Standards have been developed for single-case intervention research based on individual cases (Kratochwill et al., 2010)

• the same needs to be done for single-case intervention research based on aggregate or “clustered” cases (e.g., small groups, classrooms, schools, communities)

Kratochwill, T. R., Hitchcock, J., Horner, R. H., Levin, J. R., Odom, S. L., Rindskopf, D. M., & Shadish, W. R. (2010). Single-case designs technical documentation. Retrieved from the What Works Clearinghouse website: http://ies.ed.gov/ncee/wwc/pdf/wwc_scd.pdf

Moher, D., Schulz, K. F., & Altman, D. G. (2001). The CONSORT statement: Revised recommendations for improving the quality of reports of parallel-group randomized trials. Annals of Internal Medicine, 134, 657–662.

Potential Design Credibility Criteria for Classroom-Potential Design Credibility Criteria for Classroom-Based Single-Case Research?Based Single-Case Research?

• Control and Consideration of Extraneous Variables– Attention to teacher/classroom effects, within-school contagion effects,

school selection, history, maturation, attrition, etc.

• Randomization Requirements– Intervention randomization within classrooms– Intervention randomization across classrooms/schools– Intervention start-point randomization– Combinations of these

• Sample-Size Requirements– Number of classrooms, number of students within classrooms, number

and duration of sessions/time periods

• Replication Requirements– Intervention replication within classrooms– Intervention replication across classrooms/schools– How many of each?

Potential Evidence Credibility Criteria for Potential Evidence Credibility Criteria for Classroom-Based Single-Case Research?Classroom-Based Single-Case Research?

• Sampling Issues– Of students and classrooms, as related to external

validity/generalization of the findings

• Measurement Issues– Reliability and validity of the outcome measures

• Data-Analysis Issues– Acceptability of conclusions based on visual-analysis

procedures– Legitimacy and credibility of the statistical analyses

conducted (e.g., Type I error and power characteristics)– Legitimacy of the effect-size procedure and magnitudes of

the reported effect sizes