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 Quotient (NIQ). Statistically significant differences in typal prevalence were found for ethnicity. Using the rp(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.