An attempt was made to find a combination of MMPI scale relationships which were highly discriminating of schizophrenia. Through the use of a standardized structured interview and a diagnostic system for schizophrenia based on the use of discriminant function analysis with nonpathognomonic symptom combinations, a reliable and valid system was used to establish the criterion diagnosis. Approximately 72% of patients reliably diagnosed as schizophrenics were detected on the MMPI via a set of standard criteria (T score on Sc greater than or equal to 80 less than or equal to 100; total raw score on Sc consisted of no more than 35% K items; T score on F greater than or equal to 75 less than or equal to 95; T score on Pt less than or equal to Sc). Only 5.5% of nonschizophrenics obtained all these standard criteria on the MMPI. The assets and liabilities of these MMPI criteria to diagnose schizophrenia are discussed.

An attempt was made to assess the discriminative validity of the WIST with a sample of psychiatric inpatients. Through the use of a standardized structured interview and a diagnostic system for schizophrenia based on the use of discriminant function analysis with nonpathognomic symptom combinations, a reliable and valid system was used to establish the criterion diagnosis. Approximately 63% of patients reliably diagnosed as schizophrenic were detected via the WIST while only 14% of nonschizophrenic patients scored in the schizophrenic range on the WIST. The assets and liabilities of using the WIST to diagnose schizophrenia are discussed.