Effect of prepaid and promised financial incentive on follow-up survey response in cigarette smokers: a randomized controlled trial.
Yee Tak Derek CheungXue WengMan-Ping WangSai Yin HoAntonio Cho Shing KwongVienna Wai Yin LaiTai Hing LamPublished in: BMC medical research methodology (2019)
U.S. Clinical Trials registry (clinicaltrials.gov, retrospectively registered, reference number: NCT03297866 ).