POWER AND ACCURACY OF THE SCHMIDT AND HUNTER METAANALYTIC PROCEDURES

Many Monte Carlo studies have evaluated the Schmidt and Hunter (SandH) (1977) meta-analytic procedures for combining independent correlation coefficients and their 75% rule for testing the homogeneity of varian ce. This study is different in using simulated data that are more typi cal of those data sets included in meta-analyses (Cornwell, 1989) such that sample size, effect size, degree of range restriction, measureme nt error, and number of correlations were simultaneously manipulated i n evaluating the SandH procedures' reliability, Type I and II error, b ias, and standard error. Results supported other studies which reveale d that estimates of mean rho tend to be accurate even in the presence of small sample sizes, few correlations, and substantial measurement e rror. The power to detect variance among the rhos, however, is low in most situations; thus, the SandH procedures do not find variance among rhos when it exists (Type II error) and also have a high Type I error rate under all conditions simulated. These results are summarized in terms of the reliability of the SandH procedure in estimating mean rho and the variance of rhos.