Determinants of Item Nonresponse to Web and Mail Respondents in Three Address-Based Mixed-Mode Surveys of the General Public

Abstract

Three recent experiments demonstrate the efficacy of using mail contacts to convince address-based samples of general public household to respond to a Web survey (Smyth et. al. 2010; Messer and Dillman 2011). Results show that mailing the Web request first to respondents followed by a paper questionnaire at a later date, produced Web responses from over 1/3 of sampled respondents; the paper follow-up resulted in an additional 14-18%. This " Web+mail " design also obtained demographically dissimilar respondents via each mode: Web respondents were significantly younger with higher levels of income and education than mail respondents. Thus, it seems beneficial to off mail as an alternative to Web to increase response rates and enhance the representativeness of respondents. However, as research suggests, it could also be the case that the mail obtains higher item nonresponse compared to Web, which raises concerns about the additional value mail might add in this type of Web+mail mixed mode design. In this paper, we examine some of the determinants of item nonresponse for the Web and mail groups used in the three experiments reported in Smyth et al. (2010) and Messer and Dillman (2011). The experiments employ similar Web and mail combination strategies, questionnaire designs, and respondent demographic measures, making it possible to examine trends within and across the studies. Specifically, we report how survey mode, respondent demographics (e.g., gender, age, education, and income), and question format (e.g close-and open-end) and type (e.g., attitudinal and factual) contribute to item nonresponse rates 1 .