Intellectual assessment is central to the process of diagnosing an intellectual disability and the assessment process needs to be valid and reliable. One fundamental aspect of validity is that of measurement invariance, i.e. that the assessment measures the same thing in different populations. There are reasons to believe that measurement…

Research on the Wechsler Adult Intelligence Scale-Revised and Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) suggests that practicing clinical psychologists and graduate students make item-level scoring errors that affect IQ, index, and subtest scores. Studies have been limited in that Full-Scale IQ (FSIQ) and examiner administration,…

Professional assessment of mental retardation (MR) and learning disabilities (LD) is crucial to the implementation of P.L. 94-142 because it necessarily precedes the employment of trained teachers and because a plan for remediation depends on accurate assessment. Intelligence is a key element in the identification of MR-LD, but competent, fair…