The conceptual model of the relationship between (a) aggression trajectories and internalizing problems and (b) aggression trajectories and rule breaking. Traditional fit indices (e.g., comparative fit index, root mean square error of approximation) were not available for this analysis because of the use of numerical integration in the estimation of the categorical indicators. In this situation, means, variances, and covariances are not sufficient statistics for model estimation. Therefore, chi-square and related fit measures are not available (Muthén, 2006).