Introduction
What is new?
Key findings- •
Two modest monetary incentives, €5 cash sent with the questionnaire and entry into a draw on questionnaire completion, produced significantly higher response rates over the no-incentive arm; the cash incentive was the most effective and the most cost-effective—costing less per completed questionnaire received.
What this adds to what was known?- •
Monetary incentives are known to increase the response rates of surveys to physicians. However, optimum use of monetary incentives remains unresolved. We directly compared two modest monetary incentives—an immediate cash incentive and possible financial gain through entry into a draw, and demonstrated that both significantly increased response rates from primary care physicians, with cash being the most effective and cost-effective option.
What is the implication and what should change now?- •
Where maximum response is required, a cash incentive should be considered.
Surveys of primary care physicians (PCPs) are used in many areas of health services and policy research. However, response rates to PCP surveys can be low [1] owing to lack of time, perceived importance of studies, concerns about confidentiality, biased questions, and increasing volume and length of surveys [2], [3]. This may introduce bias and affect generalizability of the results. Dilman's Tailored Design Method (TDM) advises on questionnaire format and implementation [4] and recommends token financial incentives [5]. A range of incentives, both monetary (eg, cash or lottery tickets) and nonmonetary (eg, pens or pencils) incentives have been shown to be effective in increasing response rates to postal questionnaires in health settings (reviews and references therein Refs. [6], [7], [8], [9], [10]). However, little is known about the most effective interventions among PCP surveys, and optimum monetary incentives within this group remain unknown [7], [8]. Furthermore, many of these studies involved a mix of health care professionals and were conducted in the United States with some exceptions in China, Australia, and Britain and may not be generalizable to other health care systems [6], [7], [8], [9], [10].
We conducted a randomized controlled trial to compare the effect on response to a PCP postal survey, and the cost, of the three scenarios, namely (1) a modest direct cash incentive, (2) a small monetary incentive through inclusion in a prize draw on receipt of completed questionnaires, and (3) no incentive.