Reviews WISC-R factor analytic findings for developing a scheme for regrouping WISC-R subtests, consisting of verbal comprehension and spatial subtests. Subtests comprising these groupings are shown to have more common variance than specific variance and cluster together consistently across the samples of WISC-R scores. (Author/JAC)

Supports arguments against general use of change scores and recommends the Lord/McNemar estimates of true change. Provides a numerical example illustrating the reliability problem and the problem of the prediction of true change from various linear composites of initial and final measures. (Author)