Opposition-Defiance in the Second Year of Life: A Population-Based Cohort Study.

Recent epidemiological evidence suggests that even in the midst of the "terrible twos," frequent/severe oppositional-defiant behaviors (ODBs) are not common among toddlers and hence may be indicative of a significant opposition-defiance problem. The main objective of this study was to obtain a maximum likelihood estimate of the proportion of toddlers in the general population who are reported to exhibit ODBs on a frequent basis, and to test for gender differences therein. Data came from The Québec Longitudinal Study of Child Development, a survey of a representative birth cohort of children from the Canadian province of Québec. Multigroup latent class analysis was used to distinguish between toddlers who exhibit ODBs on a frequent basis and those who do so only occasionally or not at all. The results show that 12.4% of 17-month-old boys and girls exhibit ODBs on a frequent basis. Further, the results show a strong positive association between opposition-defiance and physical aggression early in life, with a great majority of physically aggressive toddlers exhibiting ODBs on a frequent basis. In contrast, the results show that only a minority of toddlers who may be experiencing a significant opposition-defiance problem exhibit physically aggressive behaviors on a frequent basis.