MMPI and Pyp Prediction compared to Base Rate Prediction of Six‐month Behavioral Outcome for Methadone Patients*

Discriminant functions, using the scales of the Minnesota Multiphasic Personality Inventory (MMPI) and the Pyp, a scale measuring psychopathy, were compared with base rate estimates in predicting six‐month outcome for 106 methadone patients. Employment, arrest and attrition were the behavioral categories used for group assignment in the discriminant analysis. The discriminant functions accurately classified 50 per cent of the employed and not arrested group., 57 per cent of the unemployed and not arrested group, 29 per cent of the unemployed and arrested group, and 50 per cent of the discharged group. Consideration was given to the utility of the MMPI and Pyp scales as compared to base rate predictions for each of the group classifications.