e., 30% vs. 40%) in the current design using logistic regression was .25 with alpha of .05. Randomization and Masking Participants were randomly assigned to the intervention or control arm using a computerized full read adaptive randomization program (Taves, 1974) that minimized the likelihood of imbalance between the study arms with respect to biological sex and intensity of smoking (i.e., heavy smoker [��20 cigarettes per day]) while maintaining a ratio of 2:1 in the intervention:control groups. Participants were assigned at a higher ratio to the intervention to increase the amount of information obtained about the intervention experience. Participants, but not researchers, were blind to arm allocation. Ongoing monitoring of the arm allocations revealed an imbalance in the minimum number of participants intended for each study arm within each subgroup (e.

g., male heavy smokers). As a result, allocation concealment was broken for the last eight participants enrolled. To rectify the imbalance, these participants were manually assigned to the arm subgroup that required additional participants to become balanced. For example, the control group had fewer male light smokers than it should have; as such, all seven male light smokers in the queue were assigned to the control group. The proportion of participants in each subgroup designed to balance the study arms were maintained for both arms. Procedures Smokers expressed their interest by completing an online screener form, which was then e-mailed to the project coordinator.

Eligible candidates were contacted by the project coordinator, who scheduled an appointment over the phone to confirm eligibility, explain study details, obtain verbal consent, and complete the registration process. All participants, irrespective of study arm, identified a quit day that was at least 15 days but no more than 30 days from their registration date. Those who smoked 10 cigarettes or more per day were counseled to consider pharmacotherapy to assist in their quitting (Agency for Healthcare Research and Quality, 2009). After registration, participants were e-mailed an online survey link and instructed to complete the survey as soon as possible. The baseline survey had to be completed in order to receive text messages. Both control and intervention messages began 14 days prior to one��s quit date.

Participants received incentives of $10 and $20 after completing the 4-week and 3-month postquit follow-ups, respectively. A third of participants received an additional $10 if they responded within 48hr, another third of participants received $10 GSK-3 if they completed the online survey within 48hr of receiving a second reminder text, and a different third received $10 if they completed a minisurvey via text messaging at 3 months. Participants could opt-out of the study at any time by texting ��end�� to the program or by contacting project staff.