Research note: A prenotice greeting card’s impact on response rates and response time

Maintaining high response rates over time is critical for the integrity of longitudinal studies. A best practice for encouraging survey participation in cross-sectional studies is to send sample members a pre-incentive with the survey invitation. However, in longitudinal studies this may change sample members’ future expectations of incentives. Instead researchers can use a prenotice to remind longitudinal sample members of the study and inform them of the upcoming wave. A unique greeting card format for a prenotice was experimentally tested against a $10 pre-incentive in the longitudinal study Add Health. The prenotice card, which thanked sample members for their ongoing contributions to the study over the last 20-plus years, significantly increased response rates and decreased survey response times over the 12-month course of data collection compared to the control. At the end of data collection, the prenotice card was equally effective as a $10 pre-incentive. However, in the first month of data collection, the combination of the prenotice card and pre-incentive was the most effective approach, suggesting that the best approach may depend on the planned duration of data collection. Additionally, sample members who did not participate in a previous wave had higher response rates this wave with the pre-incentive compared to the control. The findings suggest that long-term longitudinal study participants may evaluate researchers’ gratitude as a type of benefit on par with monetary incentives, offering researchers opportunities to reduce incentive costs, but this may differ based on previous wave participation.