title: Effect size and power in assessing moderating effects of categorical variables using multiple regression: a 30-year review.
abstract: The authors conducted a 30-year review (1969-1998) of the size of moderating effects of categorical variables as assessed using multiple regression. The median observed effect size (f(2)) is only .002, but 72% of the moderator tests reviewed had power of .80 or greater to detect a targeted effect conventionally defined as small. Results suggest the need to minimize the influence of artifacts that produce a downward bias in the observed effect size and put into question the use of conventional definitions of moderating effect sizes. As long as an effect has a meaningful impact, the authors advise researchers to conduct a power analysis and plan future research designs on the basis of smaller and more realistic targeted effect sizes.
authors.affiliation: The Business School, University of Colorado at Denver, Denver, CO 80217, USA. herman.aguinis@cudenver.edu
authors.forename: Herman
authors.initials: H
authors.lastname: Aguinis
authors.forename: James C
authors.initials: JC
authors.lastname: Beaty
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Boik
authors.forename: Charles A
authors.initials: CA
authors.lastname: Pierce
mesh_terms: D006801:Humans; D011584:Psychology / Q000706:statistics & numerical data*; D012044:Regression Analysis; D015203:Reproducibility of Results; D018401:Sample Size