Because of its nearness in fit to the common pathway model, we also examined the parameter estimates of the independent pathway model. For cannabis and stimulants, the overall estimates of a2, c2 and e2 were very similar and cannabis continued to have by far the largest contribution from substance-specific genetic effects. For sedatives, however, the estimate of total a2 was lower (0.40 (0.35; 0.50)) and c2 higher 0.32 (0.30; 0.35) than that seen in the independent pathway model.
