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 ¼ 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.

Little is known about what strategies are cost-effective in increasing participation among physicians in surveys that are conducted exclusively via the web. To assess the effects of incentives and prenotification on response rates and costs, general internists (N = 3,550) were randomly selected from the American Medical Association (AMA) Masterfile and assigned to experimental groups that varied in the amount of a promised incentive (none, entry into a $200 lottery, $50, or $100) and prenotification (none, prenotification letter only, or prenotification letter containing a $2 preincentive). Results indicated that the response rates were highest in the groups promised $100 and $50, respectively. While the postal prenotification letter increased response rates, the inclusion of a small token $2 preincentive had no effect on participation. Further, unlike mail surveys of physicians, the $2 preincentive was not cost-effective. Among physicians, larger promised incentives of $50 or $100 are more effective than a nominal preincentive in increasing participation in a web-only survey. Consistent with prior research, there was little evidence of nonresponse bias among the experimental groups.

Many studies rely on traditional web survey methods in which all contacts with sample members are through email and the questionnaire is administered exclusively online. Because it is difficult to effectively administer prepaid incentives via email, researchers frequently employ lotteries or prize draws as incentives even though their influence on survey participation is small. The current study examines whether a prize draw is more effective if it is divided into a few larger amounts versus several smaller amounts and compares prize draws to a small but guaranteed postpaid incentive. Data are from the 2019 Campus Climate Survey on Sexual Assault and Sexual Misconduct. Sample members include 38,434 undergraduate and graduate students at a large Midwestern university who were randomly assigned to receive: a guaranteed $5 Amazon gift card; entry into a high-payout drawing for one of four $500 prizes; or entry into a low-payout drawing for one of twenty $100 prizes. Results indicate the guaranteed incentive increased response rates, with no difference between the prize draws. While results from various data quality outcomes show the guaranteed incentive reduced break-off rates and the high-payout drawing increased item nonresponse, there were no differences across incentive conditions in rates of speeding, reporting of sensitive data, straightlining, or sample representativeness. As expected, the prize draws had much lower overall and per complete costs.

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