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Reporting Practices and APA Editorial Policies Regarding Statistical Significance and Effect Size

Colorado State University City, tvh{at}lamar.colostate.edu

Johanna E. Nilsson

University of Missouri at Kansas City, nilsson{at}umkc.edu

David R. Reetz

Indiana University, dreetz{at}indiana.edu

Teresa S. Lance

Western Michigan University, x971ance{at}wmich.edu

Bruce Thompson

Texas A&M University and Baylor College of Medicine

The recent fourth edition of the American Psychological Association Publication Manual emphasized that p values are not acceptable indices of effect and `encouraged' effect-size reporting. However, empirical studies of reporting practices of diverse journals unequivocally indicate that this new encouragement has to date been ineffective. Here two additional multi-year studies of APA journals are reported. Additionally, all 50 APA editorials that have been published since 1990 were reviewed to determine how many editors with approval have articulated policies more forceful than the APA Publication Manual's vague and seemingly self-canceling encouragement. It is suggested that changes in editorial policies will be required before improved reporting will become routine.

Key Words: effect size • hypothesis test • null hypotheses • significance tests • statistical significance

Theory & Psychology, Vol. 10, No. 3, 413-425 (2000)
DOI: 10.1177/0959354300103006


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