Is there a Day of the Week Effect on Panel Response Rate to an Online Questionnaire Email Invitation?

Abstract

Abstract Does the day of the week an email is sent inviting existing participants to complete a follow-up questionnaire for an annual online survey impact response rate? We answer this question using a preregistered experiment conducted as part of an ongoing national probability panel study in New Zealand. Across 14 consecutive days, existing participants in a panel study were randomly allocated a day of the week to receive an email inviting them to complete the next wave of the questionnaire online (N = 26,126). Valid responses included questionnaires completed within 31 days of receiving the initial invitation. Results revealed that the day the invitation was sent did not affect the likelihood of responding. These results are reassuring for researchers conducting ongoing panel studies and suggest that, once participants have joined a panel, the day of the week they are contacted does not impact their likelihood of responding to subsequent waves.