Survey return rates as a function of priority versus first-class mailing

Prior research indicates survey procedures that signal significance and individualized mailings have higher response rates. Thus, it was hypothesized that surveys delivered via Priority mail would result in higher return rates than surveys delivered via First-Class. 260 surveys were sent to individuals randomly selected from lists of licensed physical and behavioral healthcare providers in Alaska and New Mexico. Half of the selected individuals were assigned randomly to receive mailings using Priority mail, the other half received First-Class mailings. Return rate was 39% for First-Class and 35% for Priority. Z tests of proportion indicated no statistically significant differences between methods. Given increased costs with no resultant increase in response rate, sending surveys to potential participants via Priority mail does not appear warranted.