A useless raffle.
A mailed questionnaire was sent to 2712 subjects asking about respiratory symptoms, and a raffle for three prizes of 50 pounds, 30 pounds, and 20 pounds was organised. The response rate in the 1762 who were told about the raffle was no higher than for 950 subjects who served as controls.
D001363:Awards and Prizes; D004739:England; D004812:Epidemiologic Methods; D006801:Humans; D011795:Surveys and Questionnaires