The effect on response rates of offering a small incentive with a mailed questionnaire.
To determine whether response rates to a mailed questionnaire sent to population control subjects could be increased through offer of a small incentive, half of the control subjects (n = 477) in a case-control study of renal cell carcinoma were randomly selected to receive a contact letter offering a lottery ticket if a completed questionnaire was returned; the remaining subjects (n = 477) received the same letter but with no mention of a lottery ticket. Overall response rates did not differ between the two groups (72.6% versus 74.4%), although a higher percentage of those offered a lottery ticket responded without follow-up (24.4% versus 18.5%). Binomial regression modeling of the effect of the lottery ticket offer, sex, age, and percent of urban dwellers on response indicated a significant effect only for percent of urban dwellers, the rate of response increasing with a decreasing percentage of urban dwellers. The effect of sex was of borderline significance (P = 0.05), with females having the higher rate of response.
Marrett
L D
LD
OCTRF Epidemiology Research Unit, Department of Preventive Medicine and Biostatistics, University of Toronto, Ontario, Canada.
Kreiger
N
N
Dodds
L
L
Hilditch
S
S
D000328:Adult; D000368:Aged; D002292:Carcinoma, Renal Cell; D016022:Case-Control Studies; D003299:Cooperative Behavior; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms; D008297:Male; D008875:Middle Aged; D012201:Reward; D011795:Surveys and Questionnaires