We next fit the EXT-ARF model, in which externalizing phenotypes loaded onto an externalizing (EXT) factor and SUDs loaded on an addiction risk factor (ARF). Fit statistics for this model also did not meet thresholds for good fit, although fit was somewhat improved relative to the common factor model. The median standardized factor loadings were high (ƛ = 0.66), although the SD of the loadings on the ARF factor were somewhat higher (SD of ƛ = 0.27), indicating greater variability in the degree to which these factors were represented by their indicators. The EXT and ARF factors were very strongly genetically correlated (rgs = .88), suggesting they reflect largely overlapping dimensions of genetic risk. H and ωs were high for both factors, although it is important to note that the H for the ARF factor is uninterpretable given that cannabis use disorder’s loading exceeded 1.
