Using discriminant function analysis with clinical, demographic and historical variables to diagnose schizophrenia.

An effort was made to formalize the critical clinical, demographic and historical features of schizophrenia through the development of a reliable assessment questionnaire. The criterion diagnosis was established via traditional hospital procedures and was substantiated by psychometric measures. Raters with comparable diagnostic experience were familiarized with each of the clinical, demographic and historical features before evaluating the presence or absence in a sample of both psychiatric in-patients and out-patients. A structured, standardized interview was used to reduce inconsistency and oversight due to variability in interviewing techniques and coverage of psychopathology. Using the coefficients of the discriminative functions of five major symptoms (loose associations, autism, loss of ego boundaries, emotional blunting, delusions) and two demographic and historical features (family history of mental illness, poor social relations) correctly classified 98 per cent of the total sample of 253 patients. A subsequent investigation demonstrated the utility and generalizability of the proposed system. The assets and liabilities of using such an approach are discussed.

Predictive validity of the Rorschach Prognostic Rating Scale with schizophrenic patients.

The prognostic validity of the Rorschach Rating Scale was assessed with schizophrenic patients. 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. Outcome criteria used included a variety of measures of schizophrenic thought disorder. The results help to establish the practical utility of the PRS empirically with schizophrenic patients by demonstrating efficient prediction when other relevant demographic and nontest variables have been controlled. Furthermore, the concept of ego strength from which the PRS was developed does not appear to be too global a characteristic when the area for change is specifically delineated.