A multigroup Item Response Theory analysis of the Psychopathy Checklist–Revised

Item response theory was used to investigate the functioning of the Psychopathy Checklist—Revised (PCL–R; R. D. Hare, 1991, 2003) in several offender populations. With male criminal offenders (N 3,847) as a reference group, differential item functioning analyses were performed for 3 comparison groups: female criminal offenders (N 1,219), male forensic psychiatric patients (N 1,246), and male criminal offenders scored from file reviews (N 2,626). Results are discussed in the context of the 2-factor, 4-facet model for the PCL–R (R. D. Hare, 2003; J. Parker, G. Sitarenios, & R. D. Hare, 2003). Application of a multigroup graded response model to all 4 groups suggests scalar equivalence may hold at least approximately for each population, although the PCL–R provided slightly greater information about the latent trait of psychopathy for male criminal offenders scored from the standard procedure. Psychopathy is characterized by a set of affective, interpersonal, lifestyle, and socially deviant features, including egocentricity, deceptiveness, callousness, impulsivity, irresponsibility, lack of empathy or remorse, shallow emotions, poor behavioral controls, early behavior problems, and a proneness to antisocial behaviors (Cleckley, 1976; Hare, 1991). The most widely used measure of psychopathy is the Psychopathy Checklist—Revised (PCL–R; Hare, 1991, 2003), a 20-item instrument scored on the basis of interview and file information. Each item is scored as 0 (not present), 1 ( possibly present), or 2 (definitely present), resulting in total PCL–R scores that range from 0 to 40. A cut score of 30 is commonly used to distinguish individuals with psychopathy from those without psychopathy for research purposes (Hare, 1991, 2003). The PCL–R has demonstrated good internal consistency, test–retest, and interrater reliability across diverse population