As a follow-up to the analyses of alcohol consumption, assessed via the Morning Report, described above, we examined whether genotype (i.e., OPRM1 and DRD4, each tested separately) moderated the effects of Vigor and Urge to Drink in determining alcohol consumption within an episode. GEE models were conducted in which alcohol consumption (captured via morning reports) was predicted by genotype, Vigor (or Urge to Drink), and their interaction. Results revealed that alcohol consumption was predicted by Urge to Drink (GEE parameter estimate = 0.58, SE = 0.15, z score = 3.95, p < .0001), OPRM1 genotype (GEE parameter estimate = 4.73, SE = 1.81, z score = 2.62, p < .01), and their interaction (GEE parameter estimate = −0.66, SE = 0.21, z score = −3.08, p < .01). Specifically, greater urge to drink was associated with higher number of drinks, Asp40 carriers consumed a higher number of drinks, and urge to drink was less strongly associated with number of drinks consumed among carriers of the Asp40 allele within a given drinking episode. In short, these post-hoc analyses suggest that Urge
