same in the present sample (Keiley et al., 2000). In addition, studies show that rates of mental disorder increase from late childhood to adolescence, consistent with our findings of increasing rates of externalizing problems during the same time frame (D. L. Newman et al., 1996). Moreover, studies examining the age-crime curve show increases during adolescence and decreases during adulthood (Sampson & Laub, 2003), also consistent with our findings. Thus, we feel that there is theoretical and empirical support for the construct validity invariance of our measures of externalizing problems on a common metric, which permits examining the changes in externalizing problems over time.
