From the standpoint of measurement, the present findings provide strong support for the structural validity of the MTI two-factor (Detachment-Antisocial) model and invariance of this structure from late adolescence (age 17) into young adulthood (age 23). Furthermore, the present data indicated acceptable mean inter-item correlations among the items that comprise the MTI psychopathy factors – an important point given assertions that these statistics may provide a more reliable index of scale homogeneity than coefficient alphas (Schmidt, 1996). As Schmidt (1996) and others (Borsboom, 2008) have discussed, alpha is simply an indicator of how well a set of variables ‘hang’ together but does not reflect unidimensionality, given that any diverse set of positively correlated variables (e.g., IQ, education level, occupation) could provide acceptable alphas and yet involve multidimensional phenomenon. Item homogeneity (MICs) on the other hand does reflect unidimensional phenomenon. On balance, the current findings indicate that the Detachment and Antisocial factors of the MTI are unidimensional (i.e., homogenous). This is consistent with other self-report measures of psychopathy (Neumann & Declerq, 2009; Paulhus, Neumann, & Hare, in press), as well as
