The Discriminative Validity of the Whitaker Index of Schizophrenic Thinking

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.