Political Behavior

, Volume 38, Issue 2, pp 413–432 | Cite as

Turning Out Unlikely Voters? A Field Experiment in the Top-Two Primary

  • Seth J. HillEmail author
  • Thad Kousser
Original Paper


Those who turn out in American primary elections are a small and unrepresentative subset of the population. Why do citizens forgo participation in nominating contests yet vote in general elections? We argue that limited contact lowers participation in primary elections. We present results from a randomized field experiment with near 150,000 letters in California’s 2014 primary. Each letter went to one of the four million Californians who had participated in recent general elections but not in primaries. We find that a single letter increased turnout by 0.5 points from a base rate of 9.3 percent. This increase is more than twice the average effect calculated in a recent meta-analysis and represents a proportional increase of 5.4 percent. Our experiment shows that registrants who typically abstain from primaries—and who are thus often ignored by campaigns—can be effectively mobilized.


General Election Average Treatment Effect Voter Turnout Primary Election Primary Turnout 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We thank Alex Hughes and Justin Levitt for assistance in designing and conducting the experiment, and anonymous reviewers, the Editor, and Kevin Arceneaux, Greg Huber, Simeon Nichter, and Chris Tausanovitch for feedback. The experiment presented here was approved by the UCSD Human Research Protections Program, funded by the William and Flora Hewlett Foundation, and did not involve deception of its subjects. We pre-registered our analysis with The authors are solely responsible for interpretation, analysis, and conclusions. A replication archive is available at or from the authors on request.

Supplementary material

11109_2015_9319_MOESM1_ESM.pdf (512 kb)
Supplementary material 1 (pdf 512 KB)


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Department of Political ScienceUniversity of California, San DiegoLa JollaUSA

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