A pseudo-R2 of the final model was calculated by examining the squared correlation between the model’s fitted and observed values (Singer & Willett, 2003). The pseudo-R2 for the final model was .70, suggesting that the model fit the data well and accounted for 70% of the variability in externalizing problems over time. Moreover, the proportional reduction in intercept variance with the addition of the risk and protective factors to the baseline quartic model was .06. Thus, the specific risk and protective factors accounted for an additional 6% of variability in the ending values above the effects of the linear, quadratic, cubic, and quartic terms.
