Measuring the Dark Core of Personality in German: Psychometric Properties, Measurement Invariance, Predictive Validity, and Self-Other Agreement.

The Dark Factor of Personality (D)-the underlying disposition of aversive traits-has been shown to account for various ethically and socially aversive behaviors. Whereas previous findings support the reliability and validity of the original English item sets suggested to measure D, a thorough psychometric examination of their German translation is still pending. Using data from four different samples (total N > 33,000), this study comprehensively evaluates the German version of the D70, D35, and D16 with respect to (a) their factor structure, (b) measurement invariance across gender, (c) measurement equivalence with the original English item sets, (d) predictive validity for relevant outcomes across a six-month period, and (e) self-observer agreement. Results confirm the bifactor structure of the D70 and single-factor models for the D35 and the D16. Measurement invariance testing shows partial strict invariance across gender and language versions. Furthermore, predictive validity and a moderate degree of self-other agreement are supported. The German version of the D70 and its shorter versions thus allow for a psychometrically sound assessment of D.