The frequency of reliable component difference scores for the Wechsler Intelligence Scale for Children--Third edition in two samples.

The cumulative percentage frequencies are presented for differences among reliable component analysis (RCA) scores for the verbal comprehension, perceptual organization, freedom from distractibility, and processing speed constructs assessed by the Wechsler Intelligence Scale for Children--Third edition (WISC-III) for the standardization sample and a learning disabled sample. Using RCA scores to form differences has several advantages over traditional equally weighted scores for the WISC-III. J. C. Caruso and N. Cliff (2000) presented tables to assess the statistical significance of differences among the RCA scores for the WISC-III. It is important, however, to use a dual approach in interpreting difference scores; both the statistical significance of a difference and the frequency with which it occurred in a relevant comparison group should be determined. This article contains the information necessary for practitioners to use the recommended dual approach to interpreting RCA difference scores for the WISC-III.