A comparison of the Millon Clinical Multiaxial Inventory and the California Psychological Inventory in assessment of a nonclinical population

This study investigated the concurrent descriptive validity of the Millon Clinical Multiaxial Inventory (MCMI) by comparison with a widely used objective personality inventory, the California Psychological Inventory (CPI), designed to assess normal personality functioning. Due to previous findings (Repko & Cooper, 1985), it was expected that the MCMI would overestimate the prevalence of personality disorders in a nonclinical population. Subjects were 237 male and female undergraduate students enrolled in a state university. A high degree of overlap was found between many of the scales of the MCMI and CPI, which indicates assessment of a number of similar personality dimensions. Depression as measured by the Beck Depression Inventory (BDI) accounted for a significant amount of variance between the scales. Consistent with expectations, the MCMI was found to overestimate severely the frequency of personality disorders in a student population when compared to the CPI. These results are attributed to Millon's use of base rate scores that require prior knowledge of the population prevalence rate of disorders before accurate scores can be obtained for any population.