Is there more strategic voting under plurality or majority runoff? Survey evidence from presidential elections worldwide

The two electoral systems most often used for presidential elections are plurality and majority runoff. Majority runoff is more costly due to the necessity of holding a second round. However, a cited advantage of this system is that voters can vote sincerely in the first round, whereas they need to vote strategically under plurality. In this paper, I provide the first systematic test of this conjecture using an original assemblage of surveys that contain the variables necessary to capture strategic voting in presidential elections (43 elections in 19 countries between 1988 and 2021, n = 63,387). The results show that there is no less strategic desertion in the first round of majority runoff compared to plurality. This finding has important implications for the debate over the best electoral system for presidential elections.