Cost effectiveness of a prize draw on response to a postal questionnaire: results of a randomised trial among orthopaedic outpatients in Edinburgh

摘要

Postal questionnaires are frequently used in health services research and epidemiological studies. Poor response rates, however, reduce statistical power, may introduce bias, and limit generalisability. Many factors have been investigated in attempts to improve returns, and we report the results of a randomised trial to assess the cost effectiveness of a prize draw on response rates during a longitudinal study.