Diagnostic Utility of WISC-III Subtest Variability among Students with Learning Disabilities

Abstract

Psychologists have long conjectured that Wechsler subtest variability may be an indicator of learning disability. Research on intersubtest scatter (range) with previous Wechsler scales indicated that scatter could not reliably discriminate between disabled and nondisabled children. The Profile Variability Index (PVI) also failed to demonstrate adequate diagnostic utility with the WISC-R. The present study assessed the diagnostic utility of subtest variability indices on the WISC-III by comparing 684 student with learning disabilities to the 2,200 children in the standardization sample. Results of Receiver Operating Curve (ROC) analyses indicated that WISC-III subtest variability as quantified by range and variance exhibited no diagnostic utility in distinguishing between children with learning disabilities and children from the standardization sample. It was concluded that interpretation of WISC-III subtest variability has no place in the scientific practice of school psychology.

The WISC-III Profile in Greek Children with Learning Disabilities: Different Language, Similar Difficulties

“…This 3:1 male/female ratio in LD populations is not atypical (Daley & Nagle, 1996;Grice et al, 1999;Prifitera & Dersh, 1993;Watkins, 1999;Watkins et al, 2002). Children with an IQ more than 79 were included in our sample, in compliance with other studies, which propose that learning difficulties, which are observed in subjects with a lower IQ, are probably due to their lower intellectual abilities rather than to any specific disorder (Beal et al, 1996;Mayes et al, 1998).…”

Diagnostic Utility of the Learning Disability Index

“…Therefore, more appropriate ROC methods (McFall & Treat, 1999;Swets et al, 2000) were applied in this study to assess the accuracy of the WISC-III LDI in diagnosing students with learning disabilities. (Watkins, 1996(Watkins, , 1999Watkins, Kush, & Glutting, 1997a, 1997bWatkins & Worrell, 2000). When considered within the broader negative context of subtest profile research (Glutting, McDermott, Konold, Snelbaker, & Watkins, 1998;Kramer, Henning-Stout, Ullman, & Schellenberg, 1987;McDermott, Fantuzzo, Glutting, Watkins, & Baggaley, 1992; McDermott & Glutting, 1997; Teeter & Korducki, 1998), the LDI is unsupported as a tool in the diagnosis of learning disabilities.…”

Psychometric Versus Actuarial Interpretation of Intelligence and Related Aptitude Batteries

“…Review of the literature on subtest analysis validity and utility (Watkins, 2003;Watkins, Glutting, & Youngstrom, 2005) showed that subtest scores, patterns, and analyses were unable to adequately identify global neurocognitive or neuropsychological defi cits presumably related to learning disability (Watkins, 1996), nor were they related to or valid for diagnosis of learning disabilities (Daley & Nagle, 1996;Glutting, McGrath, Kamphaus, & McDermott, 1992;Hale & Raymond, 1981;Hale & Saxe, 1983;Kahana et al, 2002;Kavale & Forness, 1984;Kline, Snyder, Guilmette, & Castellanos, 1992;Livingston et al, 2003;Maller & McDermott, 1997;Mayes, Calhoun, & Crowell, 1998;McDermott, Goldberg, Watkins, Stanley, & Glutting, 2006;McGrew & Knopik, 1996;Mueller, Dennis, & Short, 1986;Ree & Carretta, 1997;Smith & Watkins, 2004;Th orndike, 1986;Ward, Ward, Hatt, Young, & Mollner, 1995;Watkins, 1999Watkins, , 2000Watkins, , 2003Watkins, , 2005Watkins & Glutting, 2000;Watkins & Kush, 1994;Watkins, Kush, & Glutting, 1997a, 1997bWatkins, Kush, & Schaefer, 2002;Watkins & Worrell, 2000). Furthermore, subtest analyses were not valid in the classifi cation of behavioral, social, or emotional problems (Beebe, Pfi ff ner, & McBurnett, 2000;…”