Factor structure of the MCMI basic personality scales and common-item artifact.

The eight basic personality scales of the Millon Clinical Multiaxial Inventory (MCMI) were derived from Millon's theory of personality, but the adequacy of the MCMI for measuring Millon's personality constructs has never been assessed. One major problem with using factor analysis to illuminate the structure of the MCMI personality scales is that artifactual structure may result from item overlap among the scales. To analyze this, item-overlap coefficients were factored and compared to the factor structures of five subject samples. For the eight basic personality scales, three factors emerged for the overlap matrix and each of the five sample matrices: Aloof-Social, Aggressive-Submissive, and Lability-Restraint. It was concluded that these three factors are inconsistent with Millon's theory and that they will be found artifactually across a wide variety of populations due to overlapping items.