Recruiting survey respondents to mailed surveys: controlled trials of incentives and prompts.
Three controlled experiments tested the efficacy of 1) a postcard or telephone prompt, 2) a lottery, 3) monetary incentives, and 4) questionnaire length to recruit adult survey respondents to a random sample of residences in San Diego, California, during 1986-1988. In experiment 1, the group randomly assigned to receive a telephone call prenotification plus the lottery incentive responded 26-66% more frequently than did controls (p = 0.02) after a single mailing. The postcard plus lottery was 17-54% more effective than no intervention with controls (p = 0.05). A second mailing of the survey weakened these effects. In experiment 2, the group randomly assigned to receive a two-page survey with the lottery announcement responded 69% more frequently after one mailing (p = 0.03) and 53% more frequently after a second mailing (p = 0.04) than the group that received an eight-page survey without the lottery incentive. The shorter form alone or the lottery alone did not increase response rates significantly relative to the long form without a lottery. In experiment 3, a monetary incentive of $5.00 contingent on response to the second mailing of the survey increased the rate of response from initial "nonresponders" by 100% relative to control who received no incentive (p = 0.03) and 75% over those who received $1.00 not contingent on response (p = 0.04). Little sampling bias and no reactivity was attributable to the recruitment procedures.
Spry
V M
VM
Graduate School of Public Health, San Diego State University, CA 92182.
Hovell
M F
MF
Sallis
J G
JG
Hofsteter
C R
CR
Elder
J P
JP
Molgaard
C A
CA
D000328:Adult; D003625:Data Collection / Q000379:methods*; D004812:Epidemiologic Methods; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D009042:Motivation; D012494:Sampling Studies; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013689:Telephone