International questionnaire postal response rate: an experiment comparing no return postage to provision of International Postage Vouchers--"Coupon-Réponse International".

Abstract

BACKGROUND: Previous studies of methods to increase response rates on international postal surveys did not include providing return postage. We provided International Postage Vouchers--"Coupon-Réponse International" to cover this. The objective of this study was to see if these International Postage Vouchers had an effect on response rates. METHODS: Between-groups, randomized, after-only. RESULTS: There was no difference in response rates between the group that received International Postage Vouchers and the group that did not. (p = 0.23). CONCLUSION: International Postage Vouchers--"Coupon-Réponse International" have no effect on response rates for international postal surveys.