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ERIC Number: EJ782475
Record Type: Journal
Publication Date: 2007
Pages: 26
Abstractor: Author
Reference Count: 47
ISSN: ISSN-1076-9986
Combining Correlation Matrices: Simulation Analysis of Improved Fixed-Effects Methods
Hafdahl, Adam R.
Journal of Educational and Behavioral Statistics, v32 n2 p180-205 2007
The originally proposed multivariate meta-analysis approach for correlation matrices--analyze Pearson correlations, with each study's observed correlations replacing their population counterparts in its conditional-covariance matrix--performs poorly. Two refinements are considered: Analyze Fisher Z-transformed correlations, and substitute better estimates of correlations in the conditional covariances. Fixed-effects methods with and without each refinement were examined in a Monte Carlo study; number of studies and the distribution of within-study sample sizes were varied. Both refinements improved element-wise point and interval estimates, as well as Type I error control for homogeneity tests, especially with many small studies. Practical recommendations and suggestions for future methodological work are offered. An appendix describes how to transform Fisher-Z (co)variances to the Pearson-r metric. (Contains 5 figures and 6 notes.)
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Publication Type: Journal Articles; Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A