Incremental validity of WISC-III profile elevation, scatter, and shape information for predicting reading and math achievement

The use of cognitive subtest profiles to hypothesize about children's learn ing strengths and weaknesses implicitly assumes that subtest profiles are p redictive of academic performance. To test this assumption, Wechsler Intell igence Scale for Children-Third Edition (WISC-III) subtest profiles were de composed into elevation, scatter, and shape components and sequentially reg ressed onto reading and math achievement scores for 1,118 nonexceptional an d 538 exceptional students. Profile elevation was statistically and practic ally significant for both exceptional (R = .36-.61) and nonexceptional (R = .72-.75) students. Profile scatter did not aid in the prediction of achiev ement. Profile shape accounted for an additional 5%-8% of the variance in a chievement measures. It was concluded that using WISC-III subtest scatter a nd shape to predict academic performance was not supported by the accumulat ed scientific evidence.