Nine variables predicted individuals’ slopes of externalizing problems over time. To understand how each of these 9 risk factors was associated with changes in externalizing problems over time, we probed the effects with plots. We created separate plots to examine the effect of low (1 SD below the mean) and high (1 SD above the mean) values of each risk factor on the slopes of externalizing problems over time. Examining the plots showed that some predictors of the slopes were related to the initial values of externalizing problems. In these instances, the slopes converged over time for low and high levels of the risk factor. Because the slopes converged from different starting points, the effects of the risk factors on the slopes were detected as significant. The observation that the risk factors related to the initial values of externalizing problems was confirmed empirically by setting the intercepts to the initial rather than ending values in a separate model. The following predictors were characterized by higher initial values of externalizing, yet smaller increases or greater decreases in externalizing problems over time:
