Publications [#251564] of Harris M. Cooper

Peer-reviewed journal articles published

1. Hedges, LV; Cooper, H; Bushman, BJ (1992). Testing the null hypothesis in meta-anatysis: a comparison of combined probability and confidence interval procedures. Psychological Bulletin, 111(1), 188-194. [doi]
   (last updated on 2024/01/01)

   Abstract:
   Combined significance tests (combined p values) and tests of the weighted mean effect size are both used to combine information across studies in meta-analysis. This article compares a combined significance test (the Stouffer test) with a test based on the weighted mean effect size as tests of the same null hypothesis. The tests are compared analytically in the case in which the within-group variances are known and compared through large-sample theory in the more usual case in which the variances are unknown. Generalizations suggested are then explored through a simulation study. This work demonstrates that the test based on the average effect size is usually more powerful than the Stouffer test unless there is a substantial negative correlation between within-study sample size and effect size. Thus the test based on the average effect size is generally preferable, and there is little reason to also calculate the Stouffer test.