Physician response rates to a telephone survey: effects of monetary incentive level.

THE Center for Disease Control (CDC) and Opinion Research Corporation (ORC) conducted an experiment to determine the effectiveness of paying physicians monetary incentives for their participation in a 20-30-minute telephone interview on the subject of influenza immunization. The test was administered to a subsample of physicians in a nationwide study of primary-care physicians: general and family practitioners, internists, pediatricians, and industrial doctors. The overall objective of the study was to measure attitudes and practices of physicians concerning influenza immunization and the impact of the federally funded Immunization Program on their practices. To enhance response rates for all physicians, the research design called for: a letter explaining the study addressed to "Dear Colleague" from the Director of the Center for Disease Control; a personal letter from the ORC project director enclosing the CDC director's letter and guaranteeing anonymity; a promise that participants would receive a copy of the report; and an expression of willingness to interview the doctor by appointment, either by telephone or in person. To maximize response rates, consideration was given to offering incentives to physicians. A literature search indicated that monetary incentives had been effective in stimulating response rates to mail surveys among the general population and special populations. (See Robertson and Bellenger, 1978; Goodstat and Chung, 1977; Kanuk and Berenson, 1975;