Psychometric Properties and Measurement Invariance of the Youth Psychopathic Traits Inventory - Short Version among Portuguese Youth Pedro Pechorro 1,2 & Diana Ribeiro da Silva 3 & Daniel Rijo 3 & Rui Abrunhosa Gonçalves 1 & Henrik Andershed 4 Published online: 21 March 2017 # Springer Science+Business Media New York 2017 Abstract This study aimed to examine the psychometric prop- erties of the Youth Psychopathic Traits Inventory - Short version (YPI-S) among a mixed-gender sample of 782 Portuguese youth (M = 15.87 years; SD = 1.72) collected in a school context. Exploratory and confirmatory factor analysis offered support for the expected 3-factor structure. Partial cross-gender measure- ment invariance and cross-sample measurement invariance of the YPI-S using a forensic sample of institutionalized males was established. The Portuguese version of the YPI-S showed ade- quate psychometric properties in terms of internal consistency, mean inter-item correlation, corrected item-total correlation, con- vergent validity, and discriminant validity. In support for criterion-related validity, the YPI-S also showed statistically sig- nificant associations with self-reported conduct disorder symp- toms, alcohol abuse, and drug use. In terms of known-groups validity, males from the school sample scored lower than males from the forensic sample and higher than females from the school sample. The YPI-S seems to be a valuable brief and psychomet- rically reliable and valid self-report measure, which can be used to assess psychopathic traits in diverse samples of youth. Keywords Assessment . Measurement invariance . Youth psychopathic traits inventory - short . Validation The constellation of affective, interpersonal, and behavioral deviant traits, referred to as psychopathy (Cooke and Michie 2001; Hare 2003), has proven to be of great value when iden- tifying the most early, severe, and stable forms of antisocial behavior (Leistico et al. 2008; Pechorro et al. 2012). The need for early identification is justifiable since psychopathy is con- sidered a high risk condition with a progressive impairment and a decreased therapeutic response over time (Ribeiro da Silva et al. 2012, Ribeiro da Silva et al. 2013, Ribeiro da Silva et al. 2015; Salekin 2010, 2015; Salekin et al. 2012). Research on the study of psychopathy in children and youth has gained widespread attention over the past decades (Salekin and Lynan 2010). These research efforts have led the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association APA 2013) to add a specifier for Conduct Disorder, which covers the diagnostic criteria for the affective component of psychopathy, considered by many to be the core element of this disorder (e.g., Cleckley, 1941/1988). There are several self-report measures that can be used to assess psychopathic traits in youth (see Ribeiro da Silva et al. * Pedro Pechorro ppechorro@gmail.com Diana Ribeiro da Silva diana.rs@fpce.uc.pt Daniel Rijo drijo@fpce.uc.pt Rui Abrunhosa Gonçalves rabrunhosa@psi.uminho.pt Henrik Andershed henrik.andershed@oru.se 1 School of Psychology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 2 Faculty of Psychology and Education Sciences, University of Coimbra, Rua do Colégio Novo, 3001-802 Coimbra, Portugal 3 Research Unit of the Cognitive-Behavioral Research and Intervention Center, Faculty of Psychology and Education Sciences, University of Coimbra, Rua do Colégio Novo, 3001-802 Coimbra, Portugal 4 School of Law, Psychology, and Social Work, Örebro University, 70182 Örebro, Sweden J Psychopathol Behav Assess (2017) 39:486–497 DOI 10.1007/s10862-017-9597-7 Author's personal copy