Northampton Electronic Collection of Theses and Research

Effect size estimates: current use, calculations, and interpretation

Fritz, C. O., Morris, P. E. and Richler, J. J. (2012) Effect size estimates: current use, calculations, and interpretation. Journal of Experimental Psychology: General. 141(1), pp. 2-18. 0096-3445.

Item Type: Article
Abstract: The Publication Manual of the American Psychological Association (American Psychological Association, 2001, 2010) calls for the reporting of effect sizes and their confidence intervals. Estimates of effect size are useful for determining the practical or theoretical importance of an effect, the relative contributions of factors, and the power of an analysis. We surveyed articles published in 2009 and 2010 in the Journal of Experimental Psychology: General, noting the statistical analyses reported and the associated reporting of effect size estimates. Effect sizes were reported for fewer than half of the analyses; no article reported a confidence interval for an effect size. The most often reported analysis was analysis of variance, and almost half of these reports were not accompanied by effect sizes. Partial eta squared was the most commonly reported effect size estimate for analysis of variance. For t tests, 2/3 of the articles did not report an associated effect size estimate; Cohen’s d was the most often reported. We provide a straightforward guide to understanding, selecting, calculating, and interpreting effect sizes for many types of data and to methods for calculating effect size confidence intervals and power analysis.
Uncontrolled Keywords: Effect size
Subjects: B Philosophy. Psychology. Religion > BF Psychology > BF180 Experimental psychology
Q Science > QA Mathematics > QA273 Probabilities. Mathematical statistics
B Philosophy. Psychology. Religion > BF Psychology > BF76.5 Psychology research
Creators: Fritz, Catherine O, Morris, Peter E and Richler, Jennifer J
Publisher: American Psychological Association
Faculties, Divisions and Institutes: University Faculties, Divisions and Research Centres - OLD > School of Social Sciences (to 2016)
University Faculties, Divisions and Research Centres - OLD > Faculty of Health & Society > Psychology
Faculties > Faculty of Health & Society > Psychology
Date: February 2012
Date Type: Publication
Page Range: pp. 2-18
Journal or Publication Title: Journal of Experimental Psychology: General
Volume: 141
Number: 1
Language: English
DOI: https://doi.org/10.1037/a0024338
ISSN: 0096-3445
Status: Published / Disseminated
Refereed: Yes
Related URLs:
URI: http://nectar.northampton.ac.uk/id/eprint/5665

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