The utility of the MMPI-2 malingering discriminant function index in the detection of malingering: a study of criminal defendants

This study examined the utility of the Minnesota Multiphasic Personality Inventory-2's (MMPI-2) malingering discriminant function index (M-DFI), recently developed by Bacchiochi and Bagby, in the detection of malingering in a forensic sample. Criminal defendants were divided into "malingering" and "not malingering" groups using the structured interview of reported symptoms (SIRS) criteria proposed by Rogers. Logistic regression analysis (LRA) revealed that the MMPI-2 infrequency (F) scale had the best predictive utility of the traditional infrequency scales. Although the M-DFI did significantly differentiate the malingering from the not malingering groups, it did not add significantly to the predictive utility of the MMPI-2 F scale. Receiver operating characteristics analyses demonstrated acceptable sensitivity and specificity for the MMPI-2 F scale, but poor sensitivity for the M-DFI scale. The results are discussed in terms of the utility of the M-DFI in detecting malingering and problems of extending the findings of simulation studies to the forensic context.