National survey of physicians to determine the effect of unconditional incentives on response rates of physician postal surveys.

Objectives: Physicians are a commonly targeted group in health research surveys, but their response rates are often relatively low. The goal of this paper was to evaluate the effect of unconditional incentives in the form of a coffee card on physician postal survey response rates.

Design: Following 13 key informant interviews and eight cognitive interviews a survey questionnaire was developed.

Participants: A random sample of 534 physicians, stratified by physician group (geriatricians, family physicians, emergency physicians) was selected from a national medical directory.

Setting: Using computer generated random numbers; half of the physicians in each stratum were allocated to receive a coffee card to a popular national coffee chain together with the first survey mailout.

Interventions: The intervention was a $10 Tim Hortons gift card given to half of the physicians who were randomly allocated to receive the incentive.

Results: 265 (57.0%) physicians completed the survey. The response rate was significantly higher in the group allocated to receive the incentive (62.7% vs 51.3% in the control group; p=0.01).

Conclusions: Our results indicate that an unconditional incentive in the form of a coffee gift card can substantially improve physician response rates. Future research can look at the effect of varying amounts of cash on the gift cards on response rates.