One interpretation for these effects on the slopes is that the risk factors did not have enduring effects. Alternatively, the slopes could reflect a self-righting characteristic of development (Kohlberg, LaCrosse, & Ricks, 1972), which could be due to efforts families and individuals make to rein in uncomfortably high levels of behavior problems, whatever their source, as in the study concerning parental campaigns of increased involvement and control of the child (Goodnight, Bates, Pettit, & Dodge, 2008). Or, more simply it could reflect a statistical law, regression to the mean, where elevations resulting from risk factors eventually returned to typical levels. Another risk factor was associated with the slopes in different ways. Higher peer deviance in later adolescence was associated with greater increases in externalizing problems over time compared to lower peer deviance. Re-centering the intercepts to different points in development (e.g., Muthén & Muthén, 2000) showed that the effect of peer deviance in later adolescence on slopes of externalizing problems became significant in later adolescence (age 15) and remained significant in adulthood.
