The Effect of Stamped Versus Franked Outgoing Envelopes on Mail Survey Response Rates

This study examined the effects of stamped versus franked envelopes on the response rate to a survey of the New Zealand general public. The experiment was conducted during the first mailout only. One group received the survey material in a plain white easy-seal envelope with a 45c stamp affixed. The other group received identical material in identical envelopes, except that the name "MASSEY UNIVERSITY, PALMERSTON NORTH, NEW ZEALAND " was printed in blue ink in the top left hand corner, and the envelopes were franked. Neither the stamped nor the franked sponsored envelope made any significant difference to the response rate at any stage in the survey. Both treatments achieved response rates of approximately 30 % to the first mailout, and a final response rate of around 63 % after three mailouts