Me ta-Analytic Procedures for Es tima tion of Effect Sizes ’ in Experiments Using Complex Analysis of Variance

This paper presents techniques for use in meta-analytic research to estimate effect sizes when studies involve complex ANOVA, ANOVA with repeated measures, and complex ANOVA with repeated measures. Real examples are also provided to show the application of the techniques. Since the pioneering work of Glass, McGaw and Smith (1981) and the works of Hunter, Schmidt and Jackson (1982) and Rosenthal (1984), meta-analysis has been widely used by researchers to review the empirical literature. The technique requires that researchers, in dealing with experimental studies, compute the effect size for a particular study in order to cumulate the results across studies. Problems, however, arise when the independent variables used in the study have more than two levels or when the experimental study under review uses analysis of variance (ANOVA) with repeated measures. Currently available effect size formulae are limited to experimental studies in which the independent variables have only two levels. This is acknowledged by Hunte