Faculty Publications

Title

requivalent, meta-analysis, and robustness: An empirical examination of Rosenthal and Rubin's effect size indicator

Document Type

Article

Keywords

Computer simulation, Effect size, Meta-analysis, Normal distribution

Journal/Book/Conference Title

Educational and Psychological Measurement

Volume

68

Issue

1

First Page

42

Last Page

57

Abstract

Rosenthal and Rubin introduced a general effect size index, r equivalent, for use in meta-analyses of two-group experiments; it employs p values from reports of the original studies to determine an equivalent t test and the corresponding point-biserial correlation coefficient. The present investigation used Monte Carlo-simulated meta-analyses to examine the impact on requivalent effect sizes of research using independent-groups, pooled-variance t tests with that using a less powerful median test. As expected, estimates based on t were higher. These differences were consistent even in the presence of strong variance heterogeneity when data were distributed normally, but not when data were nonnormal. The results suggested that the use of requivalent be confined to combining studies using inferential tests with comparable power and robustness; they also cast doubt on the use of requivalent when data are not distributed normally. © 2008 Sage Publications.

Original Publication Date

1-1-2008

DOI of published version

10.1177/0013164407301542

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