The utility of the MMPI and the MSI for identifying a sexual offender typology

Abstract

Sexual offenders are known to be heterogeneous in their behavior and their psychologic functioning; however, studies of their heterogeneity have focused on standard measures of psychopathology rather than on measures of sexual deviance. The purpose of the current study was to determine if the Multiphasic Sex Inventory (MSI) would be more effective in developing a typology than the instrument most often used in sexual offender studies, the MMPI. Incarcerated sexual offenders in the Nebraska and Florida prison systems were chosen and multivariate cluster analyses were conducted using both their MMPI scores and their scores from the MSI. Results suggested that the MSI was more effective in determining clinically different subgroups of sexual offenders. These subgroups were independent of victim maturity and victim gender, and the results were consistent regardless of geographic location. The characteristics which differentiated the subgroups suggested the need for somewhat different treatment approaches for each subgroup.