Temporal Stability of WISC-III Subtest Composite: Strengths and Weaknesses.

Abstract

The Wechsler Intelligence Scale for Children-Third Edition (D. Wechsler, 1991; WISC-III) is often used to identify subtest-based cognitive strengths and weaknesses that are subsequently used to generate interventions. Given that intelligence is presumed to be an enduring trait, cognitive strengths and weaknesses identified via subtest analysis should also be stable over time. This was evaluated with 579 students who were twice tested with the WISC-III. Based on 66 subtest composites, 6 or 7 interpretable cognitive strengths and weaknesses were found on each WISC-III administration. However, subtestbased strengths and weaknesses replicated across test-retest occasions at chance levels (Mdn ϭ .02). Because subtest-based cognitive strengths and weaknesses are unreliable, recommendations based on them will also be unreliable.

Interpreting Intelligence Test Results for Children with Disabilities: Is Global Intelligence Relevant?

“…Many sources for clinical practice describe methods of idiographic interpretation of individual strengths and weaknesses, and discourage the interpretation of global scores when they are composed of divergent cognitive processes (e.g., Flanagan & Kaufman, 2004;Kamphaus, 2001;Sattler, 2001). However, others have argued for nomothetic interpretation at the global intellectual score level, as only these summative scores have the sufficient reliability and validity necessary for individual interpretation (Jensen, 1998;McDermott et al, 1990McDermott et al, , 1992Watkins & Canivez, 2004). Despite admonishments to the contrary (e.g., McDermott et al, 1990McDermott et al, , 1992, many practicing clinicians report using profile interpretation of intelligence test results below the FSIQ (Pfeiffer, Reddy, Kletzel, Schmelzer, & Boyer, 2000), suggesting objective idiographic interpretation methods must be developed to optimize concurrent and predictive validity and avoid diagnostic and treatment error.…”

“…At the Index level, the unique ability is most likely a Broad Cognitive Ability in Cattell-Horn-Carroll parlance, while shared variance that crosses Indices may reflect relationships among stimulus properties, underlying neuropsychological processes, or response mode requirements. Index scores are reliable and stable over time (Watkins & Canivez, 2004;Wechsler, 2003), and appear interpretable across a variety of groups (e.g., Flanagan & Kaufman, 2004), suggesting they have sufficient psychometric integrity for interpretation. For a child with a disability such as LD, ADHD, or TBI, the present study replicates previous findings (e.g., Fiorello et al, 2001;Hale et al, 2001) suggesting interpretation of Index scores is warranted and necessary.…”

Significant Factor Score Variability and the Validity of the WISC-III Full Scale IQ in Predicting Later Academic Achievement

“…Despite the popularity of subtest score analysis, current research fails to support this practice (McDermott & Glutting, 1997;Watkins & Canivez, 2004;Watkins & Kush, 1994). Nevertheless, the debate about which scores to interpret continues, particularly in the prediction of academic achievement scores.…”

Construct validity of the Wechsler Abbreviated Scale of Intelligence and Wide Range Intelligence Test: Convergent and structural validity.

“…Although some have argued that clinical assessments require that a "comprehensive" battery of intelligence tests be administered to fully understand the nature of performance deficits in the context of individual profiles, research on various subtest analyses (i.e., subtest strengths and weaknesses or unique profiles) reveals them to lack sufficient reliability and validity (Canivez & Watkins, 1998, 1999Glutting, McDermott, Konold, Snelbaker, & Watkins, 1998;Glutting, McDermott, Watkins, Kush, & Konold, 1997;Macmann & Barnett, 1997;McDermott, Fantuzzo, Glutting, Watkins, & Baggaley, 1992;Watkins & Canivez, 2004). The incremental validity (Haynes & Lench, 2003;Hunsley, 2003;Hunsley & Meyer, 2003) of factor-based scores of more "comprehensive" measures of intelligence has been questioned and found lacking (Glutting, Youngstrom, Ward, Ward, & Hale, 1997;Kahana, Youngstrom, & Glutting, 2002;Konold, 1999;Ree & Earles, 1991;Ree, Earles, & Treachout, 1994;Watkins & Glutting, 2000;Watkins, Glutting, & Lei, 2007;Youngstrom, Kogos, & Glutting, 1999).…”