Psychometric properties of the 12 items Dark Triad of Personality Scale (Dirty Dozen Scale) in Ecuadorian adolescents: Analysis from the Classical Test and Item Response Theory

The objective is to analyze the validity of the 12 items Dark Triad of Personality Scale (Dirty Dozen Scale; DDS) under the precepts of Classical Test Theory (CTT) and Item Response Theory (IRT) in a sample of Ecuadorian adolescents. The methodology is a descriptive and instrumental study with a sample of 5,132 adolescents, 50.2 % male and 49.8 % female; aged between 11 and 20 years, attending schools in nine cities in the Province of Tungurahua, Ecuador. About the results, from the perspective of CTT, the evidence suggests that the DDS presents a bi-factor internal structure with adequate fit indicators. Furthermore, it has an appropriate internal consistency for both the specific factors (Machiavellianism, Psychopathy, and Narcissism) and the general factor. From the perspective of IRT, all items have appropriate discrimination and difficulty, with item 4 best aiding the interpretation of the latent construct of the Dark Triad of Personality. In conclusion, the DDS is a valid and reliable scale for use with Ecuadorian adolescents, demonstrating optimal functionality from several theoretical models of measurement.