effect size

Alternative formulas for the standardized mean difference

The standardized mean difference (SMD) is surely one of the best known and most widely used effect size metrics used in meta-analysis. In generic terms, the SMD parameter is defined as the difference in population means between two groups (often this difference represents the effect of some intervention), scaled by the population standard deviation of the outcome metric.


Between-case SMD for single-case designs


Single-case design effect size calculator


Parker, Vannest, Davis, and Sauber (2011) proposed Tau-U as an effect size measure for use in single-case designs that exhibit baseline trend. In their original paper, they actually conceptualize Tau-U as a family of four distinct indices, distinguished by a) whether the index includes an adjustment for the presence of baseline trend and b) whether the index incorporates information about trend during the intervention phase.

Standard errors and confidence intervals for NAP

Parker and Vannest (2009) proposed non-overlap of all pairs (NAP) as an effect size index for use in single-case research. NAP is defined in terms of all pair-wise comparisons between the data points in two different phases for a given case (i.

Special Education Pro-Sem

Yesterday evening I again had the pleasure of visiting Dr. Barnes’ pro seminar for first year students in Special Education, where I shared some of my work on research synthesis and meta-analysis of single-case research.

Correlations between standardized mean differences

Several students and colleagues have asked me recently about an issue that comes up in multivariate meta-analysis when some of the studies include multiple treatment groups and multiple outcome measures.

Measurement-comparable effect sizes for single-case studies of free-operant behavior

Single-case research comprises a set of designs and methods for evaluating the effects of interventions, practices, or programs on individual cases, through comparison of outcomes measured at different points in time. Although there has long been …

Four methods for analyzing partial interval recording data, with application to single-case research

Partial interval recording (PIR) is a procedure for collecting measurements during direct observation of behavior. It is used in several areas of educational and psychological research, particularly in connection with single-case research. …

Design-comparable effect sizes in multiple baseline designs: A general modeling framework

In single-case research, the multiple baseline design is a widely used approach for evaluating the effects of interventions on individuals. Multiple baseline designs involve repeated measurement of outcomes over time and the controlled introduction …