Identification of random responding on the MMPI-A.

Although substantial research literature on the effects of random responding on the MMPI-2 exists, there is very limited data available on this issue with the MMPI-A. The purpose of this study was to evaluate the utility of selected MMPI-A validity scales in detecting differences in response patterns between protocols produced by 354 adolescents assessed in clinical settings and a group of 354 randomly produced MMPI-A protocols. Results indicate that MMPI-A validity and basic clinical scales differ significantly between random and clinical groups and that MMPI-A validity Scales F, F1, F2, and VRIN appear to be most useful in correctly identifying protocols from actual clinical participants versus randomly generated response patterns. Findings are discussed in terms of the dramatic effects of the sample base rate for random responding on overall classification accuracy results. Furthermore, it was noted that the optimal cutting scores for MMPI-A Scales F, F1, F2, and VRIN were largely consistent with interpretive recommendations found in the test manual (Butcher et al., 1992) when the relative frequency of random response protocols to clinical protocols was evaluated at a ratio of 1:10. Finally, future recommendations for evaluation of the F1-F2 difference score and the TRIN scale are offered in terms of the most relevant research designs to evaluate these measures.