The effects of MMIPI-A T-score elevation on classification accuracy for normal and clinical adolescent samples

In this investigation we examined the ability of the Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A; Butcher et al., 1992) to classify accurately both clinical and normal adolescents using 2 different T-score elevation ranges, T greater than or equal to 60 and T greater than or equal to 65, and using 2 different clinical base rates for the occurrence of psy chopathology. A clinical base rate of 50% and 20%, respectively, were creat ed by comparing a clinical sample of 203 adolescent inpatients with cooccur ring substance abuse and psychiatric disorders with 2 subsamples from the M MPI-A normative group. These subsamples consisted of 203 adolescents matche d for sex and age, and a larger subsample of 1,015 adolescents proportionat ely matched for sex and ape, with the clinical group. Classification accura cy analyses revealed that although clinical base rate did affect the accura te classification of cases, a T-score cutoff of 65 resulted in higher level s of accurate classification overall while minimizing the misclassification of both clinical and normal cases. Implications of these findings for the recommended use of the MMPI-A "gray zone" are presented, and the relative a reas of strength and weakness of the MMPI-A. are reviewed in the identifica tion and description of psychopathology.