A Factor Analytic Investigation of the Millon Adolescent Clinical Inventory - Second Edition in Justice Involved Youth

The Millon Adolescent Clinical Inventory – Second Edition (MACI-II; Millon et al., 2020) is an adolescent self-report measure of personality and psychopathology. Its predecessor, the Millon Adolescent Clinical Inventory (MACI; Millon et al., 1993) is one of the most frequently used measures in forensic evaluation of justice involved youth (Archer et al., 2006; Baum et al., 2009; Viljoen et al., 2010). The factor structure of the MACI has been evaluated in diverse psychiatric and juvenile justice samples (e.g., Adkisson et al., 2002; Newman et al., 2015; Romm et al., 1999, Salekin, 2002; Woodland et al., 2014) and inconsistent findings have emerged, raising questions regarding construct validity. Notably, no factor analytic study has been conducted on the MACI-II. This study explored the MACI-II factor structure in a justice involved youth sample and the normative clinical sample. An invariant three dimensional solution emphasizing Internalizing, Externalizing, and Underlying Anger was identified. Results suggested invariance in MACI-II factor structures across diverse samples. This study provides psychometric evidence to support admissibility of the MACI-II in a court setting and allows for more nuanced interpretation of MACI-II scale elevations. That latter should, theoretically, result in better informed psycho-legal decisions.