Comparison of WAIS-III short forms for measuring index and full-scale scores.

This investigation assessed the ability of the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) short forms to estimate both index and IQ scores in a large, mixed clinical sample (N = 809). More specifically, a commonly used modification of Ward's seven-subtest short form (SF7-A), a recently proposed index-based SF7-C and eight-subtest short form (SF8) were evaluated. All three SFs proved adequate for estimating verbal comprehension, perceptual organization, and full-scale intelligence within considerably less time relative to an SF11 that provides full measurement of WAIS index scores. The SF7-A provided the best combination overall in terms of psychometric performance and estimated time savings. However, SF8 best represents all four factors and allows measurement of processing speed. The SF7-C was most hampered by inclusion of the Block Design subtest in the current assessment, but may prove advantageous in future extensions to the WAIS-IV.