Randomization
UC
HOLIDAYS
Prior to study initiation, unblinded research personnel used computer software to randomize study identification numbers into 3 groups (UC, PPKAY, and PPKAY with Standard Booster) for Stage 1; 2 groups for Stage 2 (PPKAY or PPKAY with Standard Booster); and 2 groups for Stage 3 (the best performing arm in Stage 2 or PPKAY with Personalized Booster). We utilized block randomization for all three stages without any further restrictions. We chose a 12-block randomization to keep block size consistent through each stage, which allowed enrollment of even numbers of patients in each arm over the course of enrollment to reduce potential biases given the alcohol use differences per week, month, season or during holidays.