Late Responding in Web and Mail Surveys: A Systematic Review and Meta-Analysis

There is a fundamental concern that respondents who complete a survey with a certain delay or only after one or more additional contact attempts are less motivated to provide high quality survey data. Given the rise of web surveys to being the currently most widely used mode of the survey method, this concern has increased, and surveyors wonder which mode to choose best. With a systematic review and a meta-analytic approach, we clarify types of and issues in “late responding”, and we address the questions of whether and to what extent late responding is different for web surveys compared to mail surveys. The systematic review reveals that only a third of the 74 studies included report on data quality for any type of late responding. Moreover, a wide range of definitions for late responding was identified, with essentially three types. With a meta-analytical approach, a mean share of 27% (CI: 23%–31%) of late responding across both modes was quantified, and no mode difference was found. A moderator analysis with 16 sample and survey characteristics did not identify a robust moderator across modes. In addition, our article provides a detailed overview  of different survey practices used in web and mail surveys.