Using implementation intentions prompts to enhance influenza vaccination rates
- aOperations and Information Management Department, The Wharton School, University of Pennsylvania, Philadelphia, PA 19104;
- bGraduate School of Business, Stanford University, Stanford, CA 94305;
- cSchool of Management, Yale University, New Haven, CT 06520; and
- dDepartment of Economics and
- eHarvard Kennedy School, Harvard University, Cambridge, MA 02138
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Edited by Jose A. Scheinkman, Princeton University, Princeton, NJ, and approved April 29, 2011 (received for review February 24, 2011)

Abstract
We evaluate the results of a field experiment designed to measure the effect of prompts to form implementation intentions on realized behavioral outcomes. The outcome of interest is influenza vaccination receipt at free on-site clinics offered by a large firm to its employees. All employees eligible for study participation received reminder mailings that listed the times and locations of the relevant vaccination clinics. Mailings to employees randomly assigned to the treatment conditions additionally included a prompt to write down either (i) the date the employee planned to be vaccinated or (ii) the date and time the employee planned to be vaccinated. Vaccination rates increased when these implementation intentions prompts were included in the mailing. The vaccination rate among control condition employees was 33.1%. Employees who received the prompt to write down just a date had a vaccination rate 1.5 percentage points higher than the control group, a difference that is not statistically significant. Employees who received the more specific prompt to write down both a date and a time had a 4.2 percentage point higher vaccination rate, a difference that is both statistically significant and of meaningful magnitude.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: kmilkman{at}wharton.upenn.edu.
Author contributions: K.L.M., J.B., J.J.C., D.L., and B.C.M. designed research; K.L.M., J.B., J.J.C., D.L., and B.C.M. performed research; K.L.M., J.B., and B.C.M. analyzed data; and K.L.M., J.B., J.J.C., D.L., and B.C.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1103170108/-/DCSupplemental.
Freely available online through the PNAS open access option.














