Incremental validity of the MMPI-2 Restructured Clinical (RC) scales in a private practice sample

Building on results reported in Sellbom, Graham, and Schenk (2005), in this study, we examined the incremental validity of the newly introduced MMPI-2 (Butcher et al., 2001) Restructured Clinical (RC) scales (Tellegen et al., 2003) over both the Clinical and Content scales. Participants were 647 clients in private practice who were administered the MMPI-2 and the Multiaxial Diagnostic Inventory (Doverspike, 1990) early in therapy. The results indicate that the RC scales had acceptable internal consistency, reduced intercorrelations (compared to the Clinical scales), and promising convergent and discriminant validity. Hierarchical regression analyses revealed that the RC scales added incrementally to both the Clinical and Content scales in predicting self reported clinical symptoms. These findings suggest that the RC scales are relatively homogenous measures of core clinical constructs that can add unique information to the understanding of private practice clients above and beyond the Clinical and Content scales.