Turing's game and the clinical significance of outcome with borderline patients at a day hospital

Clinical significance of a treatment effect is indicated when a treated patient, after discharge, cannot be distinguished clinically from a person who is functioning on some criterion level in terms of adjustment and normality. This principle is demonstrated in a questionnaire follow-up of patients at a day hospital. Defining the criterion level, a sex- and age-matched nonpatient group completed the same questionnaire. On the basis of the questionnaires, four judges independently guessed whether or not each respondent was an ex-patient. The agreement among the judges was high, and their classification agreed with that of a discriminant analysis in eventually declaring approximately 25% of the patients to be nonpatients. A simple model was proposed to account for the judges' performance.