Even more relevant to the structure of ODD, a recent study by Witkiewitz et al. (2013) utilized factor mixture modeling (FMM) to examine lifetime diagnoses (i.e., data collected longitudinally) of externalizing disorders (ODD, CD, ADHD, substance use disorders, and adult antisocial behavior) along the dimensional-categorical spectrum. Fully continuous latent variable models fit the observed data better than fully categorical or mixed models. Furthermore, ODD fell on a factor with ADHD, CD, and adult antisocial behavior, whereas another factor emerged for substance use disorders and adult antisocial behavior (i.e., adult antisocial behavior shared variance with both factors). The findings by Witkiewitz et al. (2013) suggest that ODD, at least within the context of other externalizing disorders across the period from age 6 years to early adulthood, has a dimensional latent structure. Nonetheless, research specifically examining the latent structure of ODD is needed. In fact, replicating such findings using taxometric analyses would be ideal given that taxometric procedures and FMM are mathematically distinct, are based on different sets of assumptions, and may arrive at qualitatively different results that are not directly comparable—even
