ABSTARCT
Background: High attrition among research participants
undermines the validity and generalizability of field research. This study
contrasted two incentivizing methods-money orders (MOs) or rechargeable
incentive cards (RICs)-with regard to rates of participants' study engagement
and follow-up contact over a 6-month period.
METHODS:
Substance
abusers (N = 303) in Los Angeles, California were recruited and randomized to
either an MO (control) or RIC (experimental) condition. All participants were
asked to call the researchers at the beginning of each calendar month for the
ensuing 5 months to update their locator information, even if nothing had
changed. Each call resulted in a $10 payment, issued immediately via the RIC
system or by MO by mail. Research staff located and interviewed all
participants at Month 6. Contact logs assessed level of effort required to
locate participants and conduct follow-up interviews.
RESULTS:
Relative
to controls, RIC participants, especially those with low ability to defer
gratification, initiated more monthly calls. Six-month follow-up rates did not
differ between RIC (75%) and controls (79%), though the RIC condition was
associated with an average staff time savings of 39.8 minutes per study
participant.
DISCUSSION:
For
longitudinal public health research involving itinerant study participants, the
RIC method produces a modest benefit in study engagement and reduced staff time
devoted to participant tracking and payments. However, the overall
cost-effectiveness of this approach will depend on the pricing model of the
card-issuing vendor (which in turns depends on the scale of the project, with
per-unit costs falling for larger projects).
- 1 Department of Psychiatry and Biobehavioral Sciences, UCLA , Los Angeles , California , USA.
- 2 School of Public Policy, Pepperdine University , Malibu , California , USA.
- 3 Department of Criminology, Law and Society, UC Irvine , Irvine , California , USA.
- Subst Use Misuse. 2016 Mar 23:1-6.
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