This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted 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 Algina, J. Articles by Keselman, H. J. Search for Related Content Social Bookmarking                         What's this?

Approximate Confidence Intervals for Effect Sizes

University of Florida

H. J. Keselman

University of Manitoba

This article defines an approximate confidence interval for effect size in correlated (repeated measures) groups designs. The authors found that their method was much more accurate than the interval presented and acknowledged to be approximate by Bird. That is, the coverage probability over all the conditions investigated was very close to the theoretical .95 value. By contrast, Bird’s interval could have coverage probability that was substantially below .95. In addition, the authors’interval was less likely than Bird’s method to present an overly optimistic portrayal of the effect. They also examined the operating characteristics of the Bird interval for effect size in an independent groups design and found that, although it is fairly accurate in its approximation of coverage probability, the accuracy of the approximation does vary with the magnitude of the population effect size.

Key Words: effect size • confidence interval • between-subjects design • within-subjects design

Educational and Psychological Measurement, Vol. 63, No. 4, 537-553 (2003)
DOI: 10.1177/0013164403256358


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

This article has been cited by other articles:

				A. R. Gilpin requivalent, Meta-Analysis, and Robustness: An Empirical Examination of Rosenthal and Rubin's Effect Size Indicator Educational and Psychological Measurement, February 1, 2008; 68(1): 42 - 57. [Abstract] [PDF]

				J. Algina, H. J. Keselman, and R. D. Penfield Effect Sizes and their Intervals: The Two-Level Repeated Measures Case Educational and Psychological Measurement, April 1, 2005; 65(2): 241 - 258. [Abstract] [PDF]