A new effect size representing the predictive power of an independent variable from a multiple regression model is presented. The index, denoted as r[subscript sp], is the semipartial correlation of the predictor with the outcome of interest. This effect size can be computed when multiple predictor variables are included in the regression model…

Shows how to test the hypothesis that a nonnested model fits a set of predictors when modeling multiple effect sizes in meta-analysis. Illustrates the procedure using data from previous studies of the effectiveness of coaching on performance on the Scholastic Aptitude Test. (SLD)