Pinchbeck, Carla E. (2014) Examining the Capacity of the MMPI-2 and MMPI-2-RF to Distinguish Between Diagnostic Groups. Coursework Masters thesis, University of Southern Queensland. (Unpublished)
Abstract
The MMPI-2 was developed for use in medical and psychiatric clinics as a clinical tool for screening and discriminating between different clinical conditions. However, previous research has challenged the assumption that individuals with different clinical diagnoses reveal distinct profiles of tests scores on the MMPI-2. In 2008 a full revision of the inventory, the MMPI-2-RF, was published and utilised a more contemporary theoretical approach to test development than its predecessor. The aim of the current dissertation was to examine whether the changes in scale development and structure on the MMPI-2-RF improved the ability to discriminate between clinically distinct diagnostic groups. The first study replicated the study by Henry (2004) and examined the ability of the MMPI-2 to discriminate between three distinct diagnostic groups, Chronic Pain (CP), Post Traumatic Stress Disorder (PTSD) and Traumatic Brain Injury (TBI), drawn from archival cases consisting of 2989 valid MMPI-2 cases assessed as part of personal injury claims in the United States and Australia. Graphical distributions of mean profile scores across all MMPI-2 scales revealed very high correlations between the three diagnoses. Discriminant Function Analysis (DFA) using Clinical scales and subscales as well as Content scales and Content Component scales on the MMPI-2 incorrectly classified approximately 50% of diagnoses and replicated Henry’s findings. MMPI-2-RF protocols derived from the same data were examined in Study 2. An examination of mean profile scores across all MMPI-2-RF scales also revealed high correlations between the three diagnostic groups for Higher Order, Psychopathology Five, Restructured Clinical, and Specific Problem scales. DFA revealed inadequate classification rates across all scale groups on the MMPI-2-RF and that the MMPI2-RF was no better at discriminating between these three clinical groups than its predecessor. The final study utilised principal component analysis to examine whether reducing the complexity of the 42 scales on the MMPI-2-RF would provide a more refined set of measures with which to discriminate between different clinical disorders. Results identified a sevencomponent final solution that provided the least number of factors and accounted for 72% of the total variance. The mean profile of scores across the seven components revealed moderate correlations between the three diagnostic groups, with the three profiles sharing only 12% to 28% of their variance. DFA on the seven components revealed that only 43.2% of cases were correctly allocated to their known diagnosis. While the accuracy of classification rates was greatest for the TBI group (47.7%) the difference was marginal with low rates of classification also shown for CP (38.5%) and PTSD (43.6%) groups. Despite the refined componential structure of the test, the capacity of the MMPI-2-RF to discriminate between different clinical disorders was not improved and error rates remained too high to warrant the use of either the MMPI-2 or MMPI-2-RF in discriminating between different clinical conditions. An implication of the findings is that clinicians are cautioned against making inferences about trends in prototypical patterns based on mean scores derived from different groups. Clinical and research practices that rely on the applicability of group behaviour to inform the interpretation of individual cases is vulnerable to high levels of error.
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| Item Type: | Thesis (Non-Research) (Coursework Masters) |
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| Item Status: | Live Archive |
| Additional Information: | Current UniSQ staff and students can request access to this thesis. Please email research.repository@unisq.edu.au with a subject line of SEAR thesis request and provide: Name of the thesis requested and Your name and UniSQ email address |
| Faculty/School / Institute/Centre: | Historic - Faculty of Health, Engineering and Sciences - School of Psychology, Counselling and Community (1 Jul 2013 - 31 Dec 2014) |
| Supervisors: | Graeme Senior |
| Qualification: | Doctor of Psychology (Clinical) |
| Date Deposited: | 20 Nov 2025 03:31 |
| Last Modified: | 20 Nov 2025 03:31 |
| Fields of Research (2008): | 17 Psychology and Cognitive Sciences > 1799 Other Psychology and Cognitive Sciences > 179999 Psychology and Cognitive Sciences not elsewhere classified |
| Fields of Research (2020): | 52 PSYCHOLOGY > 5299 Other psychology > 529999 Other psychology not elsewhere classified |
| URI: | https://sear.unisq.edu.au/id/eprint/52668 |
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