Sample Size Determination The sample size calculation for this Randomized Clinical Trial, based on the success quit rates from our previous smoking cessation study (23), indicates that 138 subjects will be required to have 80% power with two-sided 0.05 significance level test to detect a difference of at least 20% quit rate (24 week CQR) between treatment groups. Allowing for a conservative attrition rate of approximately 50%, the target number of participants will be increased to a total of 300.