Randomized trial of $20 versus $50 incentives to increase physician survey response rates.

Background: Recent experiences of survey researchers suggest that physicians are becoming less willing to complete surveys.
Objective: To compare response rates to a mailed physician survey with a prepaid check incentive of $20 versus $50.
Research Design: Randomized controlled trial.
Subjects: Five hundred seventy-eight physicians caring for patients with lung or colorectal cancer in northern California.
Measures: Proportion of physicians responding to the survey.
Results: Overall, 60.0% of physicians responded to the survey. The response rate was 52.1% for physicians who received a $20 check versus 67.8% for physicians who received a $50 check (P < 0.001). Similar differences in response rates were seen in strata by physician sex, year graduated from medical school, and survey version (all P < 0.001). More than 42% of physicians who received a $50 check responded to the first mailing, compared with only 30.8% of those who received a $20 check (P < 0.001).
Conclusions: Among physicians caring for patients with lung cancer or colorectal cancer in northern California, a $50 check incentive was much more effective than a $20 check incentive at increasing response rates to a mailed survey. As physicians become increasingly burdened with surveys, larger incentives may be necessary to engage potential respondents and thus maximize response rates.