Concurrent Validity of Wechsler Adult Intelligence Scales–Third Edition Index Score Short Forms in the Canadian Standardization Sample

Abstract

This study evaluated the concurrent validity of estimated Wechsler Adult Intelligence Scales—Third Edition (WAIS-III) index scores using various one- and two-subtest combinations. Participants were the Canadian WAIS-III standardization sample. Using all possible one- and two-subtest combinations, an estimated Verbal Comprehension Index (VCI), an estimated Perceptual Organization Index (POI), and an estimated Working Memory Index (WMI) were generated by prorating relevant subtest scores. As expected, two-subtest short forms were consistently more accurate than one-subtest short forms. Agreement between short-form and full-form index scores was high for two-subtest combinations (range = 88% to 96%) but only moderate with one subtest (range = 62% to 79%). Accuracy did not vary by age, ethnicity, gender, or education. However, accuracy was lowest for index scores in the high average to very superior range. These results suggest that although some two-subtest short forms are useful for estimating VCI, POI, and WMI scores, one-subtest short forms should not be used for this purpose.