Relevance & Research Question: Many surveys today are challenged by falling response rates or by the difficulty to recruit panel members. It is often tempting for survey practitioners to send additional reminders in order to achieve higher response rates. It is widespread agreement that several reminders and follow-up contacts do yield higher response rates. However, it is sometimes uncertain when the reminder effects are saturated and adding more reminders will no longer increase response rates, or maybe even result in negative effects by an increase in unsubscription rates from panels as a result.

Methods & Data: With an experimental set-up, using members of the Citizen Panel, a non-commercial web panel run by the Laboratory of Opinion Research at the University of Gothenburg, this study examines the impact of adding several reminders to a web survey on survey participation rates, completion rates and panel unsubscription rates. 10,000 invited respondents were randomized into four groups and assigned to receive a maximum of no reminder, one reminder, two reminders or three reminders during a three week period. Reminders were only sent to those who had not answered the survey before a certain date.

Results: The results show that going from zero to one reminder increases the participation rate by eleven percentage points, from one to two by four percentage points, and from two to three by two and half percentage points. As the number of reminders increase, the share of people who complete the entire survey after starting it also increases, as do the share of the invited sample who instead unsubscribes permanently from the panel, albeit this negative consequence becomes more pronounced only by the third reminder.

Added Value: As expected, adding more reminders increases survey participation rates. Another positive effect of adding more reminders found in this study is that they also increase completion rates, thus yielding more complete data and fewer survey breakoffs. Although adding several reminders increases participation rates and completion rates, it unfortunately also seems that it makes more people leave the panel.