Objective. To study the effects of payment timing, form of payment, and requiring a social security number (SSN) on survey response rates.
Data Source. Third-wave mailing of a U.S. physician survey.
Study Design. Nonrespondents were randomized to receive immediate U.S.$25 cash, immediate U.S.$25 check, promised U.S.$25 check, or promised U.S.$25 check requiring an SSN.
Data Collection Methods. Paper survey responses were double entered into statistical software.
Principal Findings. Response rates differed significantly between remuneration groups (χ32=80.1, p<.0001), with the highest rate in the immediate cash group (34 percent), then immediate check (20 percent), promised check (10 percent), and promised check with SSN (8 percent).
Conclusions. Immediate monetary incentives yield higher response rates than promised in this population of nonresponding physicians. Promised incentives yield similarly low response rates regardless of whether an SSN is requested.