THE EFFICACY AND ACCURACY OF THE MMPI-168 IN A FORENSIC SETTING
The purpose of this study was to investigate one of the more promising short forms, the MMPI-168, with a Forensic population. In the setting chosen, both the MMPI-399 and the MMPI-168 are used. Two hundred subjects who were legally committed to the Forensic Services Division of Middle Tennessee Mental Health Institute for 30 day court evaluations, and who completed the MMPI-399, were the primary group examined. An additional 101 subjects who did not complete the MMPI-399 but did complete the MMPI-168 were compared with the primary group on demographic variables to determine differences in the two populations. Each of the 200 MMPIs (Form R consisting of 399 items) was rescored (K-corrected), extracting the first 168 items. Next the MMPI-168 scores were analyzed in terms of three different methods: Method I used raw scores with no conversions attempted, Method II, used the Ward Conversion equations derived from psychiatric inpatients (1980), and Method III, used new regression equations derived for the Forensic subject population. These three scoring methods were then compared to the MMPI-399 scores, identified as Method IV. Comparisons were made in terms of correlations, two-point high codes, broad diagnoses and determination of antisocial and malingering behaviors. Lastly, results from all four methods were compared to each other and, more importantly, to an external criterion of final diagnosis i.e., diagnosis at the time of discharge. While most studies on the MMPI-168 have been based solely on Hit Rates or efficacy relative to the MMPI-399, this study incorporated more stringent criteria for decision-making by including examination of the accuracy of "hits". In measuring the MMPI-168 against the MMPI, the mean raw correlation was .89, T-score correlation was .87. Matching of two-point codes was 49%. In measuring against the external criterion the Hit Rate was 40% for the MMPI-168 versus a Hit Rate of 38% for the MMPI-399. The accuracy rate tended to be somewhat higher with the MMPI-168 than with the MMPI-399. The results of this study with the primary population examined indicate that using the MMPI-168 with either the Ward or Forensic Conversions seemed adequate. No need was demonstrated to develop a new conversion table for the Forensic population. (Abstract shortened with permission of author.)
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IRENE K. HERDER RATNER,
"THE EFFICACY AND ACCURACY OF THE MMPI-168 IN A FORENSIC SETTING"
ETD Collection for Tennessee State University.