title: The effects of cash and lottery incentives on mailed surveys to physicians: a randomized trial.
abstract: Low response rates, especially among physicians, are a common problem in mailed survey research. We conducted a randomized trial to examine the effects of cash and lottery incentives on response rates. A total of 4,850 subjects were randomized to one of three interventions accompanying a mailed survey-no incentive (n = 1,700), cash payment [three levels of Hong Kong dollars (HKD) $10, $20, and $40; N = 50 in each subgroup], or entry into a lottery (three levels of HKD$1,000, $2,000, and $4,000; N = 1,000 in each subgroup) on receipt of the completed questionnaire. The response rates were higher among those offered incentives than those without (19.8% vs. 16.8%, P =.012). Cash was the more effective incentive compared to lottery (27.3% vs. 19.4%, P =.017). Response also increased substantially between the first and second mailings (14.2% vs. 18.8%, P >.001). In addition, those with specialist qualifications were more willing to participate in mailed surveys. We found no significant differences in response outcomes among the various incentive arms. Cash reward at the $20 level was the most cost-effective intervention, in terms of cost per responder. Further systematic examination of the effects of different incentive strategies in epidemiologic studies should be encouraged.
authors.affiliation: Department of Community Medicine, Faculty of Medicine, University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong. gmleung@hku.hk
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.forename: Lai Ming
authors.initials: LM
authors.lastname: Ho
authors.forename: Moon Fai
authors.initials: MF
authors.lastname: Chan
authors.forename: Janice M
authors.initials: JM
authors.lastname: M Johnston
authors.forename: Fung Kam
authors.initials: FK
authors.lastname: Wong
mesh_terms: D000328:Adult; D000368:Aged; D001291:Attitude of Health Personnel; D002755:Choice Behavior; D005260:Female; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D009042:Motivation; D010820:Physicians / Q000523:psychology*; D012052:Reimbursement, Incentive; D011795:Surveys and Questionnaires; D014040:Token Economy