Contributions of Discriminant Analysis to Differential Diagnosis by Self-Report

We used discriminant function analyses of the Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1983), Millon Clinical Multiaxial Inventory (MCMI; Millon, 1983), MCMI-II (Millon, 1987), and Symptom Checklist Ninety-Revised (SCL-90-R; Derogatis, 1983) profiles from a heterogenous group of 272 psychiatric inpatients to classify patients as depressed, manic, and/or psychotic. Most functions generated from these tests significantly discriminated depressed, manic (not MCMI-II), and psychotic (not MCMI) subjects from psychiatric controls. However, there was little improvement in diagnostic efficiency over the use of single scale elevations at specified cut scores. Functions derived from the MCMI for mania and the MCMI-II for psychosis show the most promise but require replication. The difficulty of using group profile differences for the diagnosis of individual psychiatric patients is discussed.