This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Roberts, J. K. Articles by Henson, R. K. Search for Related Content Social Bookmarking                         What's this?

Correction for Bias in Estimating Effect Sizes

kroberts{at}unt.edu

Robin K. Henson

University of North Texasrhenson{at}unt.edu

Some authors debate whether effect sizes should be reported (a) for all null hypothesis tests, even non–statistically significant ones, or (b) only after a finding is first determined to be statistically significant. The decision to report and interpret small effects may partially depend on the amount of bias in the effect size measure used. Based on the recognitions that variance-accounted-for effect statistics are positively biased and that standardized difference effect sizes such as Cohen’s d can be converted into r² metrics and vice versa, the authors considered that d also may be biased. The authors therefore explored the amount of bias in Cohen’s d across a series of simulated study conditions. Results from their simulations indicated relatively no bias (close to zero) in Cohen’s d across all study conditions.

Educational and Psychological Measurement, Vol. 62, No. 2, 241-253 (2002)
DOI: 10.1177/0013164402062002003


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				R. T. Lange and G. L. Iverson Concurrent Validity of Wechsler Adult Intelligence Scales Third Edition Index Score Short Forms in the Canadian Standardization Sample Educational and Psychological Measurement, February 1, 2008; 68(1): 139 - 153. [Abstract] [PDF]

				R. K. Henson Effect-Size Measures and Meta-Analytic Thinking in Counseling Psychology Research The Counseling Psychologist, September 1, 2006; 34(5): 601 - 629. [Abstract] [PDF]

				K. Kelley The Effects of Nonnormal Distributions on Confidence Intervals Around the Standardized Mean Difference: Bootstrap and Parametric Confidence Intervals Educational and Psychological Measurement, February 1, 2005; 65(1): 51 - 69. [Abstract] [PDF]

				W.-C. Wang and H.-C. Chen The Standardized Mean Difference within the Framework of Item Response Theory Educational and Psychological Measurement, April 1, 2004; 64(2): 201 - 223. [Abstract] [PDF]

				B. Thompson What Future Quantitative Social Science Research Could Look Like: Confidence Intervals for Effect Sizes Educational Researcher, April 1, 2002; 31(3): 25 - 32. [Abstract] [PDF]