The present study had adequate data (i.e., 81 records of WPPSI-III data and 177 records of WISC-IV data) to examine the first objective as only approximately 64 participants were needed to provide sufficient statistical power (0.80) in order to detect a medium effect (i.e., d ≥ 0.50) at a significance level of α = .05 (Cohen, 1992).