MMPI-2 based classification of forensic psychiatric outpatients: an exploratory cluster analytic study

The Minnesota Multiphasic Personality Inventory (MMPI), and now the MMPI-2, are the most widely researched personality assessment tools in correctional and related forensic settings (MMPI; Hathaway & McKinley, 1940; MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989). Using the original MMPI, Megargee (1977a) and colleagues (Megargee & Bohn, 1977; Megargee & Dorhout, 1977) developed an extensive and meaningful classification system for correctional inmates. However, few studies, with the exception of Toch and Adams (1994) cluster analytic study of emotionally disturbed violent offenders, have explored possibilities of a statistically derived categorical classification paradigm within the growing population of forensic psychiatric patients awaiting discharge into the community (Bannatyne, 1996). The present exploratory study investigates the utility of a commonly employed and replicable cluster analytic method in establishing an MMPI-2-based categorical classification system within a substantial forensic psychiatric outpatient sample (N = 300). Here, we present results of a seven-cluster solution, augmented by contemporaneous Rorschach inkblot data utilizing Exner's Comprehensive System (Exner, 1991; Exner et al., 1995). Descriptive cluster characteristics are provided along with potential clinical correlates in an attempt to move closer to the goal of pairing informed assessment with effective treatment in this growing, but unique, population.