Dark Triad Dirty Dozen: Assessing its Parameters Through IRT

Abstract The present study aimed to explore the psychometric parameters of the Dirty Dozen through the Item Response Theory (IRT), using the Graduated Response Model. Participants included 284 individuals, with a mean age of 24.2 years (SD = 8.76). Initially the dimensionality of the scale was checked and results that support a three-oblique-factor structure were found (CFI = 0.99; TLI = 0.98; RMSEA = 0.03). Therefore, IRT analyses were performed separately for each factor. Then, it was verified that the items discriminate participants properly, being those items belonging to the narcissism factor the ones mostly endorsed; Machiavellianism and psychopathy demanded a greater amount of theta in order to agree with the item content, perhaps because these traits are socially undesirable. It is considered that the aims of the study were achieved, providing evidence of this short measure through the IRT, showing the possibilities of its use in future studies.