The Millon Clinical Multiaxial Inventory-III (MCMI-III) is a 175-item self-report inventory designed to assess personality characteristic and psychopathology. It has 4 validity scales, 11 clinical personality pattern scales, and 3 severe clinical syndrome scales. Although not originally validated in forensic populations, and in spite of limited research with forensic subjects, it is increasingly being used in forensic practice. Extensive changes were made in the development of the MCMI-III, limiting the applicability of the research results from prior MCMI versions.
Detection of malingering, denial, and random responding and diagnostic accuracy are critical issues that are relevant to the forensic applicability of the MCMI-III. A number of issues have implications for use of the MCMI-III in forensic assessment, including poor detection of malingering and denial, interpretation of potentially random protocols, and a significant controversy regarding diagnostic accuracy. The existence of all these issues is likely to result in vigorous challenges to expert testimony based on the MCMI-III because the instrument does not meet the criteria established in Daubert v. Merrell Dow Pharmaceuticals (1993), which require an evaluation of the error rate of assessment methods on which experts rely.
Malingering, Denial, Random Responding, and the MCMI-III
More research is needed before firm conclusions can be drawn regarding the ability of the MCMI-III to detect malingering and denial. The extant research suggests only moderate accuracy, and there are no studies that use known groups designs with forensic populations. Mike Schoenberg and colleagues in 2003 compared students simulating psychiatric disorder with psychiatric patients and found a sensitivity of 58.5% and 51.9% for a Scale Z and Scale X, respectively. Positive predictive power was 55.6% and 66.3% for X and Z, respectively. They concluded that “the MCMI-III modifier indices were of minimal clinical utility in distinguishing college student malingerers from bona fide psychiatric patients.” Somewhat better results, with higher accuracy in detecting malingering, were reported by Scott Daubert and
April Metzler, who compared two groups of psychiatric patients, one instructed to malinger and one instructed to respond honestly. In a separate study by Schoenberg and colleagues, an attempt was made to develop a discriminant equation to detect malingering. They found some improvement in detecting malingering. However, research with other instruments by Richard Rogers’s group and Kucharski and colleagues has shown that the accuracy of discriminant equations developed via simulation designs decreases to near-chance levels when applied to actual forensic populations. The results of a study by Richard Charter and Michael Lopez demonstrated that more than 50% of those responding randomly, using the VI > 1 criterion recommended in the MCMI-III manual, would be viewed as interpretable protocols. Failing to exclude random protocols potentially confounds the research on malingering and diagnostic accuracy and in clinical practice is likely to inappropriately characterize random responders as pathological.
Diagnostic Accuracy of the MCMI-III
Probably the most difficult issue confronting the MCMI-III is the current controversy regarding diagnostic accuracy. Two validity studies conducted by the test author in 1994 and 1997 and reanalyses of the data from these studies make up the findings on diagnostic accuracy. A reanalysis of the 1994 database, by Richard Rogers and colleagues, demonstrated that the convergent validities of the personality scales was “disconcertingly low ranging from .07 to .31” and that the “discriminant correlations were higher than the convergent validities.” These findings are consistent with other studies conducted by Paul Retzlaff. Frank Dyer and Joseph McCann argued that the Rogers and colleagues study was flawed due to selection of poor criterion measures and use of data from the 1994 validation study, where there were obvious deficiencies in the diagnostic criterion. The 1997 validation study attempted to address this limitation by including a Diagnostic and Statistical Manual of Mental Disorders (fourth edition; DSM-IV) of the American Psychiatric Association criterion guide for diagnosis. Louis Hsu reanalyzed both the 1994 and 1997 data and found marked improvement in the diagnostic accuracy for the 1997 data. However, serious methodological flaws including criterion contamination, confirmatory bias, and availability heuristics led him to conclude that the results potentially overpredict the diagnostic accuracy of the MCMI-III. Noteworthy in the discussion of the diagnostic accuracy is the lack of any information regarding the accuracy of the Thought Disorder scale, a scale particularly relevant to criminal forensic practice.
Applicability and Admissibility of the MCMI-III
The research to date suggests that the MCMI-III has significant limitations for forensic practice in terms of its ability to detect malingering and denial. Use of the recommended VI > 1 criterion is likely to result in inappropriate inclusion of random protocols in past research studies and clinical interpretation of protocols of questionable validity. The diagnostic accuracy controversy remains an issue owing to methodological flaws in the validation studies. The diagnostic accuracy of the MCMI-III in the identification of Axis I disorders is particularly underresearched. These are important issues that must be considered in selecting an assessment instrument not only from the perspective of the best measure for the forensic task but also for the effect it will have on court proceedings, including Daubert challenges to admissibility. One would be wise to heed Robert Craig’s advice that a thorough knowledge of the research supporting the test’s applicability and limitations will best serve the interests of the client. In this regard, the paucity of studies involving forensic populations; poor detection of malingering, denial, and random responding; and the diagnostic accuracy controversy are important issues to be aware of. Experts are in agreement that the use of the computer-generated report for the MCMI-III is inappropriate because the sensitivity for detecting pathology was artificially increased, resulting in overpathologizing of the respondent. All these issues need to be resolved before the MCMI-III can be considered a useful measure in forensic practice.
- Craig, R. J. (1999). Testimony based on the Millon Clinical Multiaxial Inventory: Review, commentary, and guidelines. Journal of Personality Assessment, 73, 290-304.
- Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
- Dyer, F. J., & McCann, J. T. (2000). The Millon Clinical Inventories, research criteria of their forensic application, and the Daubert criteria. Law and Human Behavior, 24, 487-197.
- Rogers, R., Salekin, R. T., & Sewell, K. W. (1999). Validation of the Millon Clinical Muliaxial Inventory for Axis II disorders: Does it meet the Daubert standard. Law and Human Behavior, 23, 425-443.