Non-response bias in decoy condition (N = 215).

This study introduces a new randomized field experiment exploring the impact of offering a decoy charity donation incentive together with a monetary reward to increase response rates in an online survey about coronavirus fears. The study used a two-stage approach, starting with a preliminary survey to investigate participant attitudes toward different types of donations. Subsequently, an experiment was conducted wherein a less desirable £2 donation (the decoy) was introduced as an alternative to a £2 Amazon voucher (the target) within the choice set. The study sample consisted of 431 university students. They were split into three groups: a control group with a standard £2 Amazon voucher incentive (216 participants), a decoy group with the target shown first (108 participants), and a decoy group with the decoy shown first (107 participants). We found significantly higher survey completion rates in the decoy than in the control condition (82.3% vs. 74.5%). Notably, an order effect was observed–presenting the target before the decoy led to a higher completion rate (89.8%) compared to presenting the decoy first (74.8%). Importantly, the inclusion of the decoy incentive did not introduce any response bias. This study offers a proof of principle that incorporating a decoy charity donation incentive into the choice set can have a positive impact on survey participation without adversely affecting response behaviour. It demonstrates the potential of such incentives to encourage participants to complete online surveys, even when a small monetary reward is offered.