Background:
The quality of data collected in survey research is usually indicated by the response rate; therepresentativeness of the sample, and; the rate of completed questions (item-response). Inattempting to improve a generally declining response rate in surveys considerable efforts arebeing made through follow-up mailings and various types of incentives. This study examineseffects of including a scratch lottery ticket in the invitation letter to a survey.MethodQuestionnaires concerning oral health were mailed to a random sample of 2,400 adults. Asystematically selected half of the sample (1,200 adults) received a questionnaire including ascratch lottery ticket. One reminder without the incentive was sent.
Results:
The incentive increased the response rate and improved representativeness by reaching morerespondents with lower education. Furthermore, it reduced item nonresponse. The initialincentive had no effect on the propensity to respond after the reminder.
Conclusion:
When attempting to improve survey data, three issues become important: response rate,representativeness, and item-response. This study shows that including a scratch lottery ticketin the invitation letter performs well on all the three.