We conducted two different sets of analyses to assess the effect of genotype and haplotypes on the subjective responses to alcohol. Change from baseline in the subjective outcome measures was the dependent variable in the longitudinal analysis. Linear mixed effects models were used to take into account correlation due to multiple measurements per subject. The change scores were normally-distributed. Given that we have a placebo drink during the session at time 0 prior to the three alcohol drinks, this enables within-subject comparison with the placebo condition. In our analysis, we model unstructured time trend from the beginning to the end of the session, in which placebo drink is the reference time point and responses following alcohol drinks subsequent to the placebo drink are all contrasted with this reference. Thus, comparison of the genotype groups takes into account the treatment difference across time.
