Diagnostic utility of the number of Wisc-III subtests deviating from mean performance among students with learning disabilities

This paper examined the diagnostic utility of subtest variability, as represented by the number of subtests that deviate from examinees' mean IQ scores, for identifying students with a learning disability (LD). Participants consisted of the 2,200 students in the WISC-III normative sample and 684 students (Mdngrade = 5; Mage = 10.8) identified as LD. The number of subtests deviating from examinees' Verbal, Performance, and Full Scale IQ by ±3 points for normative and exceptional samples were contrasted via Receiver Operating Curve (ROC) analyses. Results indicated that LD students did not differ from normative sample children at levels above chance. It was concluded that deviation of individual subtest scores from mean IQ scores has no diagnostic utility for hypothesizing about students with learning disabilities.