Meta-Analysis for Single-Subject Research: When Does It Clarify, When Does It Obscure?
Remedial and Special Education
Comments on the percentage of nonoverlapping data (PND) approach proposed by T. E. Scruggs et al (see record 1987-29788-001) for synthesizing single-S research. The present authors take issue with the PND method, which reduces functional analyses to a 1-number summary, for the following reasons: (a) the most relevant and credible evidence from single-S designs lies in the patterns of change across time; (b) summaries based on PND may miss vital idiosyncracies in behavior within and across studies; (c) syntheses of literature based on PND may misrepresent procedural facts and outcomes; and (d) syntheses based on PND attempt, inappropriately, to draw conclusions about the relative merits of broad categories of intervention.
Salzberg, C. L., Strain, P. S., & Baer, D. M. (1987). Meta-analysis for single-subject research: When does it clarify, when does it obscure? Remedial and Special Education, 8(2), 43-48.