Meta-analysis of experiments with matched groups or repeated measures designs.

Tests for experiments with matched groups or repeated measures designs use error terms that involve the correlation between the measures as well as the variance of the data. The larger the correlation between the measures, the smaller the error and the larger the test statistic. If an effect size is computed from the test statistic without taking the correlation between the measures into account, effect size will be overestimated. Procedures for computing effect size appropriately from matched groups or repeated measures designs are discussed. The purpose of this article is to address issues that arise when meta-analyses are conducted on experiments with matched groups or repeated measures designs. It should be made clear at the outset that although this article pertains to meta-analyses of experiments with correlated measures, it does not pertain to meta-analyses of correla-