Despite the obvious advantages of detecting whether ODD is categorical (taxonic) or is the extreme of an underlying existing continuum (dimensional), research investigating the latent structure of ODD is sparse. Some researchers have examined questions pertinent to the issue. For example, Fergusson et al. (2010) examined the differential relation between ODD among older adolescents (14 to 16 years) and outcomes during late adolescence and early adulthood (primarily 18 to 25 years) when treating ODD dimensionally (i.e., symptom counts based on either self- or mother-report) versus categorically (i.e., meeting diagnostic criteria based on endorsement of four or more symptoms in a given 12-month period by either respondent). Even when controlling for a range of covariate factors, the associations between ODD and a host of subsequent potentially related outcomes—including property and violent offenses, arrests, substance use, mental health disorders, pregnancy or parenthood by age 20, interpartner violence, and poor educational or employment outcomes—were consistently higher when ODD was treated dimensionally. Furthermore, on average, the categorical models estimated only about a half as much variance in the outcomes as the dimensional models.
