Unconditional and conditional incentives differentially improved general practitioners' participation in an online survey: randomized controlled trial

Abstract

OBJECTIVES: To compare the impact of unconditional and conditional financial incentives on response rates among Australian general practitioners invited by mail to participate in an online survey about cancer care and to investigate possible differential response bias between incentive groups. STUDY DESIGN AND SETTING: Australian general practitioners were randomly allocated to unconditional incentive (book voucher mailed with letter of invitation), conditional incentive (book voucher mailed on completion of the online survey), or control (no incentive). Nonresponders were asked to complete a small subset of questions from the online survey. RESULTS: Among 3,334 eligible general practitioner..