Comparison of two computational formulas for a WAIS-R seven subtest short form

Several validity studies for a seven subtest WAIS-R short form have been conducted with patients from different populations as participants. All of these studies demonstrated high correlations between the short form IQ estimates and the actual VIQs, PIQs, and FSIQs (i.e., .90 to .98). In general, there also were small mean differences in the short form versus actual IQs across samples. There currently are two computational formulas for the seven subtest short form. The original weighted formula and a revised proration formula. This study investigated the accuracy of the two short form computational formulas in samples of patients with brain impairment. It was found that the two formulas produced nearly identical results from both statistical and clinical perspectives. Given that the formulas produce nearly identical results and the majority of published studies with this short form have used the weighted formula, we recommend that future investigators use the original weighted formula to maintain clinical and scientific consistency.