Gift Card Incentives and Non-Response Bias in a Survey of Vaccine Providers: The Role of Geographic and Demographic Factors Open Access

Van Otterloo, Joshua E. (2012)

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Gift Card Incentives and Non-Response Bias in a Survey of Vaccine
Providers: The Role of Geographic and Demographic Factors
This study investigates the effects of non-response bias in a 2010 mailed
survey assessing experiences with H1N1 influenza vaccine administration
among a diverse sample of providers (N=765) in Washington state.
Though we garnered a high response rate (80.9%) by using evidence-
based survey design elements, including intensive follow-up and a gift
card incentive from Target, non-response bias could exist if there were
differences between respondents and non-respondents. We investigated
differences between the two groups for seven variables: road distance to
the nearest Target store, practice type, previous administration of vaccines,
region, urbanicity, size of practice, and Vaccines for Children (VFC)
program enrollment. We also examined the effect of non-response bias on
survey estimates. Statistically significant differences between respondents
and non-respondents were found for four variables: miles to the nearest
Target store, type of medical practice, whether the practice routinely
administered additional vaccines besides H1N1, and urbanicity. Practices
were more likely to respond if they were from a small town or rural area
(OR=7.68, 95% CI=1.44-40.88), were a non-traditional vaccine provider
type (OR=2.08, 95% CI=1.06-4.08) or a pediatric provider type (OR=4.03,
95% CI=1.36-11.96), or administered additional vaccines besides H1N1
(OR=1.80, 95% CI=1.03-3.15). Of particular interest, for each ten mile
increase in road distance from the nearest Target store, the likelihood of
provider response decreased (OR=0.73, 95% CI=0.60-0.89). Of those
variables associated with response, only small town or rural practice
location was associated with a survey estimate of interest, suggesting that
non-response bias had a minimal effect on survey estimates. These
findings show that gift card incentives alongside survey design elements
and follow-up can achieve high response rates. However, there is evidence
that practices farther from the nearest place to redeem gift cards may be
less likely to respond to the survey.

Table of Contents


Section Page

Chapter I:

Literature Review...1

Chapter II:






Figures and Tables...25

Chapter III:

Public Health Implications...30



Additional Figures...40

Survey Tool...42

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