The effectiveness of MMPI-A items in discriminating between normative and clinical samples.

The Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A; Butcher et al., 1992) was released in 1992 and has rapidly become the most widely used objective personality assessment instrument with adolescents. Although the MMPI-A reduced or eliminated several problems associated with the use of the original MMPI (Hathaway & McKinley, 1943) with adolescents, the MMPI-A does produce a high frequency of within normal limits basic scale profiles for individuals with substantial psychopathology including adolescents in inpatient psychiatric settings. To better understand the reasons for this phenomenon, we compared the item endorsement frequencies for the MMPI-A normative sample with results from two adolescent clinical samples, and these results were contrasted to the item endorsement frequencies for the MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) normative sample and a clinical sample of adult psychiatric inpatients. Results showed that the MMPI-A contains a substantial number of items that do not show a significant difference in item endorsement frequency between normative and clinical samples. Furthermore, MMPI-A basic and content scales generally show a much lower percentage of effective items than do the corresponding scales for the MMPI-2. We discuss the findings in relation to the frequent occurrence of low range MMPI-A profiles in clinical samples and the potential usefulness of these results in future efforts to develop viable short forms for the MMPI-A.