deterioration in model fit was observed when the C component for cigarettes was dropped in combination with the C component for cannabis (Δχ2(2) =−7.41), but dropping the A pathway for alcohol resulted in a poorer fit to the data (Δχ2(2) =−7.41). As seen in Table 2, variance in these three phenotypes was best represented with an ACE model for alcohol and AE models for cigarettes and cannabis.
