Man versus model of man: A rationale, plus some evidence, for a method of improving on clinical inferences.

Clinical psychologists, physicians, and other professionals are typically called upon to combine cues to arrive at some diagnostic or prognostic decision. Mathematical representations of such clinical judges can often be constructed to capture critical aspects of their judgmental strategies. An analysis of the characteristics of such models permits a specification of the conditions under which the model itself will be a more valid predictor than will the man from whom it was derived. To ascertain whether such conditions are met in natural clinical decision making, data were reanalyzed from a study of the judgments of 29 clinical psychologists attempting to differentiate psychotic from neurotic patients on the basis of their MMPI profiles. The results of these analyses indicate that for this diagnostic task models of the men are generally more valid than the men themselves. Moreover, the finding occurred even when the models were constructed on a small set of cases, and then man and model com­ peted on a completely new set. A psychologist who works for a municipal Suicide Prevention Center uses the cues from telephone interviews to assess the probability that each of his callers will try to kill him­ self. A pathologist who works for a large Uni­ versity hospital uses medical laboratory find­ ings to assess the likelihood that each of his patients has a particular disease. A stock