Faculty Proceedings, Presentations, Speeches and Lectures


A Monte Carlo Study: Frequency of Normal Healthy Adults with Abnormal MMPI-2 Scores

Event Location / Date(s)

Marco Island, FL / November 16-19, 2011

Document Type

Conference Proceeding

Presentation Date


Conference Name / Publication Title

31st Annual Meeting of the National Academy of Neuropsychology



Objective: Previous research suggests that as more scores are interpreted, there is a coinciding increase in the likelihood that abnormal scores will be obtained. Interpretation of the MMPI-2 can involve the analysis of as many as 98 or more separate scores, which suggests potential for a high frequency of seemingly abnormal scores amongst normal healthy adults.

Method: The incidence of elevated MMPI-2 scores was calculated for the normal population using Monte Carlo simulations. Correlations amongst scales from the restandardization sample were used to determine the percentage of the population with seemingly abnormal scores. Simulations were conducted for all scales combined, and for the Clinical, Harris–Lingoes, Content, Content Component, and Supplementary scales separately at varying t-score cutoffs. Results: 36.8% of normal adults are likely to obtain a score that would otherwise be considered clinically significant at 65T on one or more of the 10 Clinical scales. The normal incidence of at least one apparently abnormal score was 38.3% on the Content, 55.1% on the Supplementary, and 71.3% on the Harris–Lingoes scales. When all scale groups are interpreted together, at least five seemingly meaningful scores will be found for about a third of normal persons, and seven or more scales that appear to be clinically significant can be expected in 25% of perfectly normal individuals.

Conclusion: These results imply that interpretation of a large number of MMPI-2 scales should be conducted with caution, and that high t-scores may be necessary for an adequate level of confidence in the absence of corroborative test scores and extra test data.

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