Estimation of the Standardized Mean Difference for Repeated Measures Designs

Abstract

This simulation study modified the repeated measures mean difference effect size, d⁼_RM , for scenarios with unequal pre- and post-test score variances. Relative parameter and SE bias were calculated for dRM ≠ versus dRM = . Results consistently favored d^≠_RM over d⁼_RM with worse positive parameter and negative SE bias identified for d⁼_RM for increasingly heterogeneous variance conditions.