The effects of cash and lottery incentives on mailed surveys to physicians: A randomized trial

Gabriel M. Leung*, Lai Ming Ho, Moon Fai Chan, Janice M. Johnston, Fung Kam Wong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)801-807
Number of pages7
JournalJournal of Clinical Epidemiology
Issue number8
Publication statusPublished - Aug 1 2002
Externally publishedYes


  • Data collection
  • Epidemiologic methods
  • Incentives
  • Motivation

ASJC Scopus subject areas

  • Epidemiology


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