Core Profiles of School-Aged Examinees from the National Standardization Sample of the Comprehensive Test of Nonverbal Intelligence.

Abstract. Profile analysis often is used to assist in the (a) determination of appropriate program placements, (b) diagnosis of learning disabilities, and (c) design of relevant interventions. Validity evidence for the interpretation of profiles, subscores, or score differences needs to be provided when the interpretation of these scores is suggested (American Education Research Association, American Psychological Association, & National Council on Measurement in Education, 1999). Taxonomies of core profiles from national standardization samples of several widely used intelligence tests have been derived using cluster analytic methods. The aim of this study was to derive core profiles from the general education subsample (N = 1,705) from the Comprehensive Test of Nonverbal Intelligence (CTONI; Hammill, Pearson, & Wiederholt, 1997) using a three-stage cluster analysis procedure. Results showed three core profile types differing by High Average, Average, and Below Average scores on the Nonverbal Intelligence Qu otient (NIQ). Statistically significant differences in typal prevalence were found for ethnicity. Using the [r.sub.p(k)] similarity coefficient, a second purpose was to look at the percentage of unique profiles found for a subsample of students with learning disabilities (N = 173) from the CTONI. standardization sample. Researchers and practitioners should anticipate a minimal number of unique CTONI test profiles because 157 (90.8%) of individuals with a learning disability were found to match one of the core profile types. Findings indicate that level, not shape, differences should be expected from administration of the CTONI to students both with and without learning disabilities. Lightner Witmer, father of applied psychology and founder of the first psychological clinic, worked with children having difficulties succeeding in school. Beginning in the late 1920s, school psychologists focused on diagnosing problems based on intelligence test results. David Wechsler (1944) claimed that the examination of intelligence test profiles was useful for clinical inferences. Today, intellectual assessment is practiced during approximately one quarter of the school psychologist's week (Goh, Teslow, & Fuller, 1981; Hutton, Dubes, & Muir, 1992; Smith, 1984; Stinnett, Havey, & Oehler-Stinnett, 1994). Profile analysis commonly is used in the interpretation of intelligence test scores (Konold, Glutting, McDermott, Kush, & Watkins, 1999; McDermott, Fantuzzo, & Glutting, 1990; McDermott, Fantuzzo, Glutting, Watkins, & Baggaley, 1992). Assessment textbooks (e.g., Kamphaus, 1993; Kaufman, 1979, 1994; Sattler, 2001) and published test manuals (e.g., Elliot, 1990; Hammill, Pearson, & Wiederholt, 1997; Kaufman & Kaufman, 1983) include sections devoted to the interpretation of profiles. Subtest or profile analysis may be used to assist with (a) determining appropriate program placements, (b) diagnosing learning disabilities, and (c) designing relevant interventions (Kaufman, 1979, 1994; Sattler, 1992; Zachary, 1990). The findings of several studies, however, do not support these uses and have shown no differences in the subtest profiles of general and special education students (Kavale & Forness, 1984; Mailer & McDermott, 1997; McDermott et al., 1990; Sexton & Street, 1985; Spreen & Haaf, 1986; Vance, Kitson, Singe r, & Brennner, 1983; Watkins & Kush, 1994). The practice of intraindividual profile analysis using ipsatized scores (regarding a statistically significant difference between an examinee's individual subtest score and personal mean across subtests as a strength or weakness) was made popular by Kaufman (1979, 1994) for hypothesis generation and score pattern interpretation. However, intelligence tests with high communality and low subtest specificity were intended to be interpreted at the global, not subtest, level, and the use of ipsatized scores with such tests has been sharply criticized (McDermott et al. …