title: Understanding the Psychopathic Personality Inventory (PPI) in terms of the unidimensionality, orthogonality, and construct validity of PPI-I and -II.
abstract: Comments on an article by Marcus et al. (see record 2011-23134-001). Marcus et al. (this issue) hold that PPI-I and PPI-II are generally orthogonal (uncorrelated). Examination of the primary PPI scales calls this into question. Specifically, the scales that make up Psychopathic Personality Inventory (PPI)-I and PPI-II are differentially correlated in offenders (Neumann et al., 2008) and college students (as reported in Lilienfeld, 1990, final sample). This pattern of correlations indicates that the socalled orthogonal association between PPI-I and PPI-II may be attributable to a statistical "washout" effect, rather than zero correlations across scales. The scales that make up PPI-I and PPI-II may also be correlated differentially with external correlates, rendering interpretation of PPI-I and PPI-II associations with such correlates ambiguous. The overlap of PPI scale scores among forensic and nonforensic samples also is problematic, particularly for the PPI-I scales.
authors: Department of Psychology.
authors: Craig S
authors: 0000-0002-3825-2153
authors: CS
authors: Neumann
authors: Department of Applied Psychology, University College Lessius.
authors: Katarzyna
authors: K
authors: Uzieblo
authors: Department of Experimental, Clinical and Health Psychology, Ghent University.
authors: Geert
authors: G
authors: Crombez
authors: Department of Psychology, University of British Columbia/Darkstone Research.
authors: Robert D
authors: RD
authors: Hare
mesh_terms: D000987:Antisocial Personality Disorder / Q000523:psychology*; D006801:Humans; D007175:Impulsive Behavior / Q000523:psychology*; D008960:Models, Psychological; D010555:Personality Inventory / Q000706:statistics & numerical data*; D012930:Social Dominance