Factor analysis of MCMI-II and PACL basic personality scales in a college sample

This study examined factor dimensions common to the eight basic personality scales of the Millon Clinical Multiaxial Inventory-II (MCMI-II; Millon, 1987) and Personality Adjective Check List (PACL; Strack, 1987, 1990). Subjects were 140 college students (65 men and 75 women). MCMI-II weighted raw scores (WRS) and WRS corrected for number of items endorsed true by regression were employed for analysis along with PACL T-scores. Principal components analyses with varimax and direct oblimin rotations were carried out separately on the two sets of MCMI-II and PACL scores. MCMI-II and PACL scales measuring the same personalities were usually correlated most highly with each other, although some divergences were noted. WRS yielded three bipolar dimensions and a fourth unipolar method factor that loaded only the five MCMI-II scales that were strongly correlated with number of items endorsed true. Residual scores yielded a more meaningful set of three bipolar dimensions labeled Social Introversion-Extraversion, Emotionality-Restraint, and Social Dominance-Submissiveness, without the method factor, that were very similar to personality dimensions found separately in the two tests. More research is needed to clarify the response bias issue in the MCMI-II and to further explicate similarities and differences between the MCMI-II and the PACL.