Skip to main content
×
Home

Baseline, Placebo, and Treatment: Efficient Estimation for Three-Group Experiments

  • Alan S. Gerber (a1), Donald P. Green (a1), Edward H. Kaplan (a2) and Holger L. Kern (a3)
Abstract

Randomized experiments commonly compare subjects receiving a treatment to subjects receiving a placebo. An alternative design, frequently used in field experimentation, compares subjects assigned to an untreated baseline group to subjects assigned to a treatment group, adjusting statistically for the fact that some members of the treatment group may fail to receive the treatment. This article shows the potential advantages of a three-group design (baseline, placebo, and treatment). We present a maximum likelihood estimator of the treatment effect for this three-group design and illustrate its use with a field experiment that gauges the effect of prerecorded phone calls on voter turnout. The three-group design offers efficiency advantages over two-group designs while at the same time guarding against unanticipated placebo effects (which would undermine the placebo-treatment comparison) and unexpectedly low rates of compliance with the treatment assignment (which would undermine the baseline-treatment comparison).

Copyright
Corresponding author
e-mail: alan.gerber@yale.edu (corresponding author)
Footnotes
Hide All

Authors' note: The authors are grateful to Mark Grebner, who conceived of the intervention described here and assisted in data collection, and to the Institution for Social and Policy Studies. We also thank the editors and anonymous reviewers, who provided very valuable comments. The experiment reported in this article was reviewed and approved by the Human Subjects Committee at Yale University. Supplementary materials for this article are available on the Political Analysis Web site.

Footnotes
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Political Analysis
  • ISSN: 1047-1987
  • EISSN: 1476-4989
  • URL: /core/journals/political-analysis
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×
MathJax
Type Description Title
PDF
Supplementary Materials

Gerber et al. supplementary material
Appendix

 PDF (194 KB)
194 KB

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 18 *
Loading metrics...

Abstract views

Total abstract views: 67 *
Loading metrics...

* Views captured on Cambridge Core between 4th January 2017 - 19th November 2017. This data will be updated every 24 hours.