It is also encouraging that the predictions in the present study were somewhat accurate: The model accounted for more than two-thirds of the variability in externalizing problems over time. The specific risk and protective factors accounted for approximately 6% of the variability in the ending values of externalizing problems at age 27 above the effects of time (linear, quadratic, etc.). The fact that considerable variance in externalizing problems appears to be explained by continuity (i.e., the effects of time) is consistent with the notion that past behavior is the best predictor of future behavior. However, continuity does not necessarily indicate stability of individuals’ levels of externalizing problems over time—there were heterogeneous patterns of change within individuals across time. Moreover, even the continuity of externalizing behavior followed a nonlinear pattern of change across time. In general, the model was somewhat accurate in predicting within-individual changes in externalizing problems from ages 5 to 27. Nevertheless, we were able to augment our predictions using specific risk factors that explained variance in externalizing problems above and beyond the strong continuity of externalizing behavior over
