MMPI-A AND RORSCHACH INDEXES RELATED TO DEPRESSION AND CONDUCT DISORDER - AN EVALUATION OF THE INCREMENTAL VALIDITY HYPOTHESIS

This investigation extends the earlier research by Archer and Gordon ( 1988) by examining the extent to which combining indices from the newl y released MMPI-A and the revised Rorschach Comprehensive System furni shes incremental validity in terms of improved diagnostic prediction. The predictive accuracy of selected MMPI-A and Rorschach variables con ceptually related to diagnoses of depression and conduct disorder were compared in a clinical sample of 152 adolescents. Results of multivar iate analyses of variance revealed some significant differences betwee n diagnostic groups on several MMPI-A scales, and 1 significant differ ence on the Rorschach involving the Vista variable. Stepwise discrimin ant function analyses resulted in 2 MMPI-A scales and 2 Rorschach vari ables that collectively accounted for a small proportion of variance i n the diagnosis of depression, and 3 MMPI-A scales that accounted for a significant component of variance in the conduct disorder diagnosis. Classification accuracy results indicated that the hit rate for depre ssion diagnosis did not improve using an optimal linear combination of the 4 variables over the rates produced by the single use of either t he MMPI-A Depression content scale (A-DEP) or Scale 2. For the conduct disorder diagnosis, the optimal linear combination of MMPI-A Conduct Problems (A-CON), Cynicism (A-CYN), and Immaturity (IMM) scales served as the best predictor, and no Rorschach variables contributed signifi cantly to classification accuracy. Our results replicated the findings of Archer and Gordon (1988) in indicating that the combined use of MM PI-A and Rorschach variables does not appear to produce incremental in creases in accuracy of diagnostic classification.