Stability of the internal structure of the millon clinical multiaxial inventory

The Millon Clinical Multiaxial Inventory (MCMI) has become increasingly popular in clinical use. Along with this, there has been more interest in the internal structure of the 20 scales of the original 175-item MCMI-I. The literature reports some agreement on four components, although both three- and five-component solutions have been reported. The degree of similarity of these components across populations remains arguable, as none of the previous studies have used quantitative measures of component similarity. The present study reports on two new samples of psychiatric patients, one of 82 cases from a general hospital and the other of 145 inpatients from a psychiatric hospital. It also reanalyzes the data from nine samples from the literature, using Tucker's coefficient of congruence and ten Berge's analysis of principal component weights (PCW). The congruence analyses showed good agreement of the first three components across samples and notably lower agreement for the fourth. The PCW analyses showed two major types of structure matrices. In the first, there was a large and dominant first component, with three smaller ones. In the second, the variance was distributed more evenly across the four components. The results are discussed in terms of the overlapping scales of the MCMI-I.This work was supported by funds from the Departments of Psychiatry and Psychology, The University of Western Ontario.