Classification Accuracy of Sequentially Administered WAIS-IV Short Forms

Abstract

A Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) short form (SF) may be effective for ruling out subnormal intelligence. To create a useful SF, subtest administration should follow the order prescribed in the manual and, depending upon individual performance, be terminated after completion of 2, 3, 4, or 5 subtests. One hundred and twenty-two patients completed the WAIS-IV. In two analyses, Full-Scale IQs (FSIQs) ≤69 and ≤79 were classified as impairment. Classification accuracy statistics indicated that all SFs using both cutoff scores exceeded the base rate (i.e., 14% and 34%) of subnormal intelligence, with hit rates ranging from 84% to 95%. The FSIQ cutoff of ≤69 had poor sensitivity for detecting impaired intellectual functioning with the 2-, 3-, 4-, and 5-subtest SFs; specificity, positive predictive value (PPV), and negative predictive value (NPV) were excellent for each SF. With the FSIQ cutoff of ≤79, sensitivity was strong to excellent for the 3-, 4-, and 5-subtest SFs as were specificity, PPV, and NPV.