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The goal of this article is to discuss psychometric issues that are important in neuropsychological assessment and to present some recent advances in empirically derived interpretation methods. The article is divided into four main sections. The first two sections provide an overview of some of the basic psychometric concepts that make up the foundation of assessment. The first section presents an overview of how the adequacy of the normative sample and me shape of the score distribution can impact me interpretation of test performance. The second section presents a review of the role of measurement error and considers how the level of scores, their rank in the distribution, and the presence of ceiling or floor effects can impact interpretation. The third section explores the issue of normal variability and the prevalence of "abnormal" test scores in healthy people. The final section provides an overview of various methods for interpreting change in test performance over time. The authors present this psychometric information in a manner that should be easily understood by most clinicians, with examples that employ commonly used neuropsychological tests, such as the Wechsler Adult InteUigence Scale-Third Edition (WAIS-IV; Wechsler, 1997a), Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV; Wechsler, 2008), Wechsler Memory Scale-Third Edition (WMS-III; Wechsler, 1997b), Wechsler Memory Scale-Fourth Edition (WMS-IV; Wechsler, 2009), Children's Memory Scale (CMS; Cohen, 1997), California Verbal Learning Test-Second Edition (CVLT-II; Delis, Kramer, Kaplan, & Ober, 2000), and the Neuropsychological Assessment Battery (NAB; Stern & White, 2003).
Keywords: neuropsychology, psychometrics, test selection, interpretation, assessment
Neuropsychological assessment has advanced considerably over the past few decades. Part of the successful advancement of neuropsychological assessment can be attributed to the increasing number of neuropsychologists in Canada who are making internationally recognised contributions to the discipline (for a discussion on the contribution of Canadian neuropsychologists over the past three decades, see Fuerst & Rourke, 1995; Hayman-Abello, Hayman- Abello, & Rourke, 2003; Rourke, Fisk, Strang, & Gates, 1981). These contributions have increased our knowledge of the neuropsychological correlates of various neurological, medical, and psychiatric disorders; improved upon existing assessment methods; lead to the development of new speciaUsed assessment techniques; and advanced the interpretive methods used in clinical and research settings.
As a result of these developments in Canada, the United States, and around the world,...