A multitrait-multimethod analysis of the MCMI-II clinical syndrome scales.

Multitrait-multimethod procedures and factor analyses were utilized to assess convergent/discriminant validity of the revised version of the Millon Clinical Multiaxial Inventory (MCMI-II) clinical syndrome scales and effects of item overlap on scale performance. Except for the Delusional Disorder Scale (PP), convergent validity was supported, but poor discriminant validity was found for the Alcohol Dependence (B) scale, Drug Dependence (T) scale, and Scale PP. Item overlap did not influence performance for many scales. In fact, results indicate that some scales, such as Bipolar:Manic (N), may perform better in overlapping form, whereas others, such as Somatoform (H) and Scales B and T, are most affected by item overlap. Factor structure was generally stable, regardless of whether overlapping or nonoverlapping scales were utilized. However, substance abuse/dependence emerged as an independent factor when common item artifact was removed. Findings are discussed in terms of their implications for clinical practice and further research.