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Which Matters Most: Party Strategic Exit or Voter Strategic Voting? A Laboratory Experiment*


There is abundant empirical evidence that the plurality rule constrains party competition and favors two-party systems. This reduction of party system fragmentation may be due to parties deciding not to enter elections for which they are not viable and/or voters voting strategically. Yet, no prior research has attempted to estimate the respective role of parties and voters in this process. To fill this gap, we conducted a unique laboratory experiment where some subjects played the role of parties and others played the role of voters, and where the two were able to respond to each other just as in real-life elections. We find that the reduction due to party strategic exit is higher than that due to strategic voting. We conclude that parties play a key role in the effect of the plurality rule on party system fragmentation.

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Damien Bol, Lecturer in Political Behaviour, Department of Political Economy, Strand Building, King’s College London, London, United Kingdom WC2R 2LS ( André Blais, Full Professor, Département de Science Politique, Université de Montréal, CP. 6128, Succursale Centre-ville, Montréal, QC, Canada H3C 3J7 ( Simon Labbé St-Vincent, Research and Planning Analyst, Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, Canada QC H3T IJ4 ( The experiment conducted for this paper was conducted within the Making Electoral Democracy Work Project, which is funded by the Social Sciences and Humanities Research Council of Canada. To view supplementary material for this article, please visit

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Political Science Research and Methods
  • ISSN: 2049-8470
  • EISSN: 2049-8489
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