After the addition of the curvilinear effects of time, the proportional reduction in intercept variance (PRV, similar to ΔR2; Peugh, 2010) was .49, suggesting that about half of the between-person differences in ending values of externalizing problems at age 27 was accounted for by the effects of time (i.e., linear, quadratic, cubic, and quartic slopes). Moreover, the positive correlations between the intercept and linear slope (r = .44) and the intercept and quadratic curvature (r = .09) suggest that the higher a person’s slope and curvature, the higher his or her ending value of externalizing problems at age 27.
