The original externalizing model11 included residual correlations between smoking initiation and problematic alcohol use and cannabis initiation and age at first sex. Although we dropped these correlations in the current analyses, as they would have necessitated cross-factor residual correlations, we tested an additional common factor model including these original residual correlations. The addition of these parameters resulted in substantial improvement in model fit (χ2 = 907, p < 0.001, AIC = 951, CFI = 0.93, SRMR = 0.10).
