Estimation and testing for differences in effect size: A comment on Hsu

Larry V. Hedges*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Responds to L. M. Hsu's proposal of a statistical procedure for testing the difference between effect sizes in independent studies. It is shown that the test proposed by Hsu is incorrect and that it tends to reject the null hypothesis of equal effect sizes too often. The statistical model underlying effect size estimation is clarified, and the exact distribution of the effect size estimator is given. The distribution is used to show that the usual size estimator is biased. (6 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).

Original languageEnglish (US)
Pages (from-to)691-693
Number of pages3
JournalPsychological bulletin
Issue number3
StatePublished - May 1982


  • statistical procedure for testing difference between effect sizes, criticism of L. M. Hsu's proposal

ASJC Scopus subject areas

  • Psychology(all)


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