A randomized trial of incentives to improve response rates to a mailed women's health questionnaire.
BACKGROUND
Mailed questionnaires can be a convenient method for collecting data on women's health, although poor response rates are a concern.


METHODS
As part of a survey of women's health conducted in Maryland in 2001, a randomized trial was performed to assess the effects of two incentives (US dollars 1.00 or a lottery ticket) as well as precontact with an introductory postcard on response rates. Questionnaires were mailed to 3000 women aged 40-60 who were randomized to one of six incentive/precontact groups: lottery/postcard, money/postcard, postcard only, lottery only, money only, or no incentive/no postcard.


RESULTS
The overall response rate was 37.6%. Each incentive/precontact group yielded a higher response rate than the no incentive/no postcard group, although only the response rates for the lottery/postcard group (41.3%) and the money only group (40.0%) were significantly higher than that of the no incentive/no postcard group (33.1%). Money was the only factor that had a significant independent effect on likelihood of response (hazards ratio [HR] compared to no incentive = 1.22, 95% confidence interval [CI] = 1.03, 1.43). Response rates were lower in minority ZIP codes, although the effects of the incentives were generally greater than in the nonminority ZIP codes.


CONCLUSIONS
These results indicate that response rates to mailed women's health questionnaires may be improved with modest incentives, particularly cash incentives.
Whiteman
Maura K
MK
Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Langenberg
Patricia
P
Kjerulff
Kristen
K
McCarter
Robert
R
Flaws
Jodi Anne
JA
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008396:Maryland; D008875:Middle Aged; D009042:Motivation; D010358:Patient Participation / Q000191:economics; D011795:Surveys and Questionnaires / Q000191:economics; D016387:Women's Health