Actuarial and Clinical Approaches to Psychodiagnosis

Abstract

This is a critical examination of the evidence and issues involved in actuarial and clinical methods of psychodiagnostic evaluation. After demonstrating that the evidence to date is inadequate and largely irrelevant to the problem, consideration is given to the basic issues involved. The basic difficulty in arriving at adequate criterion variables is stressed. The answer to the general question of which methods are superior under specified conditions is seen to lie in an area of interest to all psychology: the psychology of prediction. In the field of psychodiagnosis, two types of predictions are specified, prediction of carefully specified behavioral events and prediction of carefully specified behavioral processes. In the first, clinical judgment is required in assigning weights to prediction variables according to individual patterns. In the latter, contingency predictions about emergent behavior are required. While improvement of both actuarial and clinical methods is undoubtedly necessary, it is maintained that not actuarial methods but “human judgement, let us hope based on sufficient evidence, will always have the last word.”