2.11 SAMPLE SIZE FOR QUANTITATIVE DATA Our target sample size is 100 for each of the 2 arms. Assuming a 20% attrition rate over 6 months, we will recruit 125 patients into each arm, for a total sample size of 250. This sample size of n=100 in each group at 6 months, will give us sufficient power (>80%) to detect, at the 5% level of significance (2-sided test), an effect size of at least 0.4 for the primary outcome PHQ-9, as well as for other continuous scale outcomes. Cohen considers such an effect size as small to medium.