Abstract

Survey researchers using online data collection methods continue to invest in efforts to identify ways of improving response rates. Response speed is also of importance, particularly for surveys that use methods other than email to send remainders or to seek participation from initial nonrespondents (i.e. push-to-web mixed mode surveys), due to the additional costs associated with slow response.
Meanwhile, the tools used to improve response rates and response speed have become more sophisticated, particularly various types of adaptive designs. Within these designs, researchers no longer focus on the average effect of survey design features but are instead interested in the effect on subgroups of particular interest, namely those with otherwise low response rates or a propensity for slow response. This reflects a recognition that both outcomes of interest (response rate, response speed) and the effectiveness of design features that influence the outcomes may vary substantially over sample subgroups. In this context, panel surveys provide a particularly rich environment for the application of targeted designs as the wealth of prior information available can be used to identify subgroups (likely) variation in the outcomes of interest and to inform the choice of design features that might provide improved outcomes.
In this framework and using experimental data from the Understanding Society Innovation Panel, we focus on the day of the week on which an invitation to participate in a web survey is mailed and investigate the effect of targeted timing for the initial invitation as well as subsequent individual remainders. In order to do so, we mounted an experiment on the mixed-mode sample of Wave 9 of the panel. Half of the mixed-mode sample received the email invitation and subsequent remainders according to standard procedures, while the other half was sent the invitation and remainders depending on which day they responded to the questionnaire in previous waves of the panel. Knowledge of the response behaviour is based on paradata collected during the data collection process. We thus study whether the propensity of participation and speed of participation is different if receiving the invitation on a targeted timing basis compared to a standard one. We also examine the role of prior participation in the panel and potential differences between those who responsed on small mobile devices and others. Specifically, we speculate that people receiving the invitation on a targeted timing basis might participate immediately to the survey particularly if they can do so using a small mobile device.