on the single factor estimated in the first common factor model with 11 phenotypes. The revised common factor model with seven externalizing phenotypes provided the best fit across all specifications, and it closely approximated the observed genetic covariance matrix (i.e., χ2(12) = 390.234, AIC = 422.23, CFI = 0.957, SRMR = 0.079). This model was selected as our final factor model because it identified a genetic factor of externalizing that was suitable for genome-wide association analysis, offered an easily interpretable factor solution, and satisfied the model fit criteria. We hereafter refer to it as “the externalizing factor” (EXT).
