Psychometric Properties of the Youth Psychopathic Traits Inventory – Short Version (YPI-S): an Investigation of Factor Structure, Item Function, and Convergent and Divergent Validity

Few studies have investigated the factor structure or item functioning of the Youth Psychopathic Traits Inventory (YPI) family of measures and fewer still have investigated the short form of the YPI (Andershed, et al., 2002), the YPI-S (vanBaardewijk, et al. 2010). The current study attempts to fill a gap in the literature by investigating the factor structure and factor invariance of the YPI-S and its subscales as well as using an Item Response Theory (IRT) approach to investigate item functioning overall and differential item functioning (DIF) based on race and gender. A diverse group of high school students (N = 288, Mage = 15.53, 44.8% male, 60% White) was recruited from a mid-sized Southeastern city in the United States. Confirmatory factor analyses were conducted to determine the best-fitting factor structure which was then subjected to invariance testing across race and gender. Analyses showed good support for measure invariance across race and gender using a hierarchical factor structure. IRT analyses revealed overall strong functioning of most items. DIF analyses were conducted at the whole-measure and subscale level. At the whole-measure level no DIF was found based on race, but six items were identified as displaying DIF across gender showing greater discrimination for boys on two items (from the GM subscale) and greater discrimination for girls on four items (from the CU and II subscales). The DIF analysis suggests that there may be a difference in item functioning across gender, especially within the Grandiose-Manipulative and Callous-Unemotional subscales of the YPI-S.