Assessing the Psychometric Utility of IQ Scores: A Tutorial Using the Wechsler Intelligence Scale for Children–Fifth Edition.

IQ tests provide numerous scores, but valid interpretation of those scores is dependent on how precisely each score reflects its intended construct and whether it provides unique information independent of other constructs. Thus, IQ scores must be evaluated for their reliability and dimensionality to determine their psychometric utility. As a tutorial, the Wechsler Intelligence Scale for Children–Fifth Edition (WISC-V) scores were evaluated and it was demonstrated that the WISC-V is multidimensional, but only the Full-Scale IQ (FSIQ) was found to be sufficiently reliable for clinical use. WISC-V group factors were not well defined and WISC-V index (i.e., factor) scores were contaminated with variance from other constructs and insufficiently reliable for clinical decisions. Clinicians were encouraged to go beyond structural goodness of fit and evaluate IQ test scores in terms of their reliability and ability to provide information that is not available from the general ability score as well their predictive and treatment validity. Software was provided to assist in that evaluation. Impact Statement IQ tests provide numerous scores, but valid interpretation of those scores is dependent on how precisely each score reflects its intended construct and whether it provides unique information independent of other constructs. Thus, IQ scores must be evaluated for their reliability and dimensionality to determine their psychometric utility. This article describes an evidence-based approach that clinicians can employ to assess the psychometric utility of IQ scores, supplies software tools to assist in that analysis, and provides a tutorial example using Wechsler Intelligence Scale for Children–Fifth Edition (WISC-V) scores. [ABSTRACT FROM AUTHOR]