 The primary outcome variable of interest is difference in mean alcohol consumption previous 7 and 14 day use measured in gweek between subjects in the intervention group and the control group, and collected through a timeline follow-back assessment. A statistical test frequently used in this type of study is an independent samples t-test. We used the SPSS SamplePower calculator to estimate the sample size needed to achieve 80 power, with a two-tailed level of significance alpha of 0.05. We use the number of grams of alcohol consumed per week obtained from the 1997 Flemming trial: a mean SD of 137.7 135.7 gwk in the intervention group, and 185.5 155.2 in the control group. The sample size needed is then n146 in each arm. The average consumption in the Flemming trial was on the lower side, with a difference in mean reduction very similar to the other studies with adequate allocation concealment included in the Cochrane review. 