Evidence for validity of the differential personality inventory.

In order to check the concurrent validity of the Differential Personality Inventory (DPI), the authors gave the test to 60 psychiatric patients (25 men, 35 women), who also were observed and rated on Lorr and Vestre's Psychotic Inpatient Profile. Patients also took Whitaker's Index of Schizophrenic Thinking (WIST), a test that measures thought disorder. The patients received higher scores on appropriate scales of the DPI than did a normative group (N = 370) of university students. We predicted that six of the DPI scales would correlate with relevant criterion measures (Lorr-Vestre scales and WIST); in five of six instances such correlations were statistically significant. We conclude that the DPI discriminates psychotics from normals and that among psychotics it has a moderate power to discriminate among types of psychotic behavior.