ERIC Number: EJ885739
Record Type: Journal
Publication Date: 2010-Jun
Abstractor: As Provided
Confidence Intervals for Effect Sizes: Compliance and Clinical Significance in the "Journal of Consulting and Clinical Psychology"
Odgaard, Eric C.; Fowler, Robert L.
Journal of Consulting and Clinical Psychology, v78 n3 p287-297 Jun 2010
Objective: In 2005, the "Journal of Consulting and Clinical Psychology" ("JCCP") became the first American Psychological Association (APA) journal to require statistical measures of clinical significance, plus effect sizes (ESs) and associated confidence intervals (CIs), for primary outcomes (La Greca, 2005). As this represents the single largest editorial effort to improve statistical reporting practices in any APA journal in at least a decade, in this article we investigate the efficacy of that change. Method: All intervention studies published in "JCCP" in 2003, 2004, 2007, and 2008 were reviewed. Each article was coded for method of clinical significance, type of ES, and type of associated CI, broken down by statistical test (F, t, chi-square, r/R[superscript 2], and multivariate modeling). Results: By 2008, clinical significance compliance was 75% (up from 31%), with 94% of studies reporting some measure of ES (reporting improved for individual statistical tests ranging from [eta][superscript 2] = 0.05 to 0.17, with reasonable CIs). Reporting of CIs for ESs also improved, although only to 40%. Also, the vast majority of reported CIs used approximations, which become progressively less accurate for smaller sample sizes and larger ESs (cf. Algina & Kessleman, 2003). Conclusions: Changes are near asymptote for ESs and clinical significance, but CIs lag behind. As CIs for ESs are required for primary outcomes, we show how to compute CIs for the vast majority of ESs reported in "JCCP," with an example of how to use CIs for ESs as a method to assess clinical significance. (Contains 2 footnotes, 1 table, and 2 figures.)
Descriptors: Intervals, Effect Size, Compliance (Psychology), Clinical Psychology, Periodicals, Statistical Analysis, Editing, Multivariate Analysis, Journal Articles, Intervention, Research Reports
American Psychological Association. Journals Department, 750 First Street NE, Washington, DC 20002-4242. Tel: 800-374-2721; Tel: 202-336-5510; Fax: 202-336-5502; e-mail: email@example.com; Web site: http://www.apa.org/publications
Publication Type: Information Analyses; Journal Articles; Reports - Research
Education Level: N/A
Authoring Institution: N/A