Scratch lottery tickets are a poor incentive to respond to mailed questionnaires

BACKGROUND: It has been demonstrated that the enclosure of money with a mailed questionnaire increases the response rate significantly. We evaluated scratch lottery tickets as an alternative to cash. METHODS: 1500 randomly selected Norwegians between the ages of 40 and 65 years were sent a short questionnaire. 250 received one lottery scratch ticket worth 20 Norwegian kroner (approximately 3 US$) together with the questionnaire, 250 received two scratch tickets, and 250 were promised two scratch tickets if they replied within one week. A fourth group of 250 persons received a 50 kroner banknote with the questionnaire. The remaining 500 letters served as controls. RESULTS: The overall response rate after 6 weeks was 77%. Logistic regression analysis showed that only the 50 kroner group had a response rate that was statistically significantly higher than the controls (p < 0.0001). It was also significantly higher than that in any of the other incentive groups (p < 0.0001, p < 0.004 and p < 0.0001 respectively). Female sex (p < 0.001) and age (p < 0.002) increased the response rate significantly. CONCLUSION: It is possible that the recipients scratched their cards before completing the questionnaire, and that it was a disincentive for the majority that they did not win anything. Lottery scratch tickets are no substitute for cash as an incentive to respond to a questionnaire.