The effect of conducting a lottery on questionnaire response rates: a randomised controlled trial.
OBJECTIVE
To study the effect of a lottery incentive on questionnaire response rate.


METHODS
In Copenhagen County, Denmark, a random sample of 2543 men and women between the ages of 19 and 60 were randomised into a control group and an intervention group. Both groups were contacted by mail and asked to complete a questionnaire on sociodemografic characteristics, self-rated health and self-reported physical activity level. The intervention group was offered participation in a small lottery for returning the questionnaire. No incentive was offered to the control group.


RESULTS
The final response rate for the control group was 60.4 and 63.4% for the intervention group. Although the response rate was significantly higher in the intervention group after 2 and 3 weeks, the difference in the final response rate between groups was not statistically significant (p = 0.12). There was no statistically significant difference between groups in sociodemografic characteristics, self-rated health or self-reported physical activity level.


CONCLUSIONS
A lottery incentive had no significant effect on the overall response rate, but may have contributed to a quicker response. Furthermore a lottery incentive did not seem to alter the selection of respondents.
Aadahl
Mette
M
Research Centre for Prevention and Health, Glostrup University Hospital, Copenhagen Country, Glostrup, Denmark. meaa@glostruphosp.kbhamt.dk
Jørgensen
Torben
T
D000293:Adolescent; D000328:Adult; D003256:Community Participation / Q000706:statistics & numerical data*; D003710:Demography; D003718:Denmark; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D009042:Motivation; D018579:Patient Selection; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires