How long should surveys be left open?

Most responses come within 24 hours of sending out the first survey (about 55%), including a sizable portion within the first hour (about 18%). After the first day, without a reminder, relatively few complete. Apart from legal reasons, surveys need not be left open longer than a week. Optimally, reminders can be sent two days after the initial send. This underscores the importance of sending surveys on optimal days of the week and optimal hours of the day.

Keep in mind: The graph above has an x axis that represents the time from the initial send. It does not consider reminder sends. The percentage of completes within the first day would be higher if the chart represented hours since any email with the survey was sent.