To confirm compliance, and exclude those who were non-compliant, with the marijuana abstinence instructions, urine samples collected at baseline and 5 days abstinent were analyzed for THC–COOH metabolite levels. Individuals were excluded from the statistical analyses if their day 5 THC–COOH levels were not 50% lower than their baseline THC–COOH levels. Using the exclusion criteria noted above, 35 of the 140 participants were found to be non-compliant and as such were excluded from statistical analyses, leaving this study with a sample size of 105 individuals. However, we compared these 35 subjects who did not maintain compliance to those who did. χ2 analyses were used to compare the groups on sex and frequency of the CNR1 and FAAH SNPs. There were no differences on these variables (P > 0.05); t-tests were used to compare the groups on marijuana use variables. Although not significant, the non-compliant group was slightly higher than the compliant group in terms of the marijuana dependence score [mean = 5.8, standard deviation (STD) = 2.4 versus mean = 5.2, STD = 2.3] and slightly lower in quantity (mean
