To study the effects of payment timing, form of payment, and requiring a social security number (SSN) on survey response rates.
Third‐wave mailing of a U.S. physician survey.
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.
Paper survey responses were double entered into statistical software.
Response rates differed significantly between remuneration groups (=80.1, <.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).
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.