Test-Retest Reliability and Construct Validity of the Brief Dark Triad Measurements

Despite the widespread use of the Dirty Dozen (DD) and Short Dark Triad (SD3) as inventories for antagonist personality traits, appropriately powered studies on their test-retest reliability (rtt) are lacking. We report the 12-day rtt-s of the DD and SD3 scales. Leveraging the test-retest data, we calculated their convergent and discriminant correlations while controlling for measurement error. Median rtt-s were .87 and .90 (N = 500) for the DD and SD3 scales, respectively, substantially higher than their internal consistencies. Convergent correlations were .77, .63 and .64 for Machiavellianism, Narcissism and Psychopathy, respectively, whereas discriminant correlations between the Machiavellianism and Psychopathy scales had a median of .65, pointing to their being effectively indistinguishable traits in the SD3 and DD. The DD and SD3 items had median rtt-s of .69 and .71, respectively. We emphasize the importance of the rtt for scale development and validation.