Improving Mail Survey Response Rates Using Chocolate and Replacement Questionnaires

This study examined the effectiveness of two procedures aimed at improving response rates for mail surveys: an incentive sent with either the first mail-out or first follow-up, and the inclusion of a replacement questionnaire, with or without an incentive, with either the first or second follow-up. The survey involved a sample of 1,600 New Zealand residents aged 18 years or older, randomly selected from the 2005 Electoral Roll and randomly assigned to one of four treatment groups. The response rates after two follow-ups ranged from 62.3 to 66.5 percent. Using a chocolate as an incentive with the first mail-out was effective in generating a significantly higher initial response than the control; however, after two follow-up mail-outs, differences were not significant. Sending a replacement questionnaire plus a chocolate with the first follow-up generated a significantly higher response rate than merely sending a letter, and the effect of this procedure persisted through to the end of the survey. Overall, these results provide further compelling evidence of the importance of using follow-up mail-outs for improving mail survey response rates.