Effects of E-Mailed Versus Mailed Invitations and Incentives on Response Rates, Data Quality, and Costs in a Web Survey of University Faculty

While a large literature indicates that using a mixed-mode approach to notify or contact potential respondents can be effective in increasing response rates, surprisingly little research examines the impact the mode of invitation has on participation in a web survey. To assess the effects of invitation mode on response rates, costs, and demographic representativeness, university faculty members (N = 280) were randomly assigned to experimental groups and sent a mailed invitation letter and a $2 cash incentive; a mailed invitation letter only; or an e-mailed invitation. Nonresponding faculty received up to two reminders to participate, by e-mail. Results indicated that the response rates were higher for the groups invited using a postal letter, but the inclusion of $2 did not significantly increase the response rates. Consistent with expectations, while costs were higher for the mailed invitation groups, the mailed invitations improved the demographic representativeness of the respondents, especially for the $2 incentive group. This study builds on a small body of literature that explicitly examines the mode of invitation on survey participation in web surveys and adds to previous findings by examining costs and effects on the demographic representativeness of the respondents.