As reporting of effect sizes in evaluation studies has proliferated, researchers and consumers of research need tools for interpreting or benchmarking the magnitude of those effect sizes that are relevant to the intervention, target population, and outcome measure being considered. Similarly, researchers planning education studies with social and…

Partial correlation coefficients are often used as effect sizes in the meta-analysis and systematic review of multiple regression analysis research results. There are two well-known formulas for the variance and thereby for the standard error (SE) of partial correlation coefficients (PCC). One is considered the "correct" variance in the…

Looking times (LTs) are frequently measured in empirical research on infant cognition. We analyzed the statistical distribution of LTs across participants to develop recommendations for their treatment in infancy research. Our analyses focused on a common within-subject experimental design, in which longer looking to novel or unexpected stimuli is…

The second approach used by L. V. Hedges and L. Friedman (1993) in their reanalysis of Feingold's earlier results is conceptually equivalent and yields results consistent with the original interpretation. The first method yields results that are discrepant. Analyses of variations in tail effect sizes are planned. (SLD)

Feingold's reply illustrates that his steps in characterizing tail effect sizes are not the calculations the authors had imagined. Attempting to reproduce Feingold's calculations, the authors still often find themselves in disagreement with interpretations Feingold has placed in his table. (SLD)

Analyzes effect sizes in tails of distribution of scores in Feingold's study of joint effects of gender differences in mean and variability on 28 cognitive-ability scales. Effect sizes are smaller than Feingold assumed. Evaluates joint effect of gender differences by number of males and females in extreme score ranges. (SLD)