Effects of runoff voting rules on number of parties and candidates' political experience: Evidence from a law change in Peru

We study the effect of a change in electoral rules on political competition, measured by the number of candidates and their political experience. We explore the effects of a change in legislation, introduced a year before the gubernatorial elections in Peru on the number of parties that participated in these elections. We also investigate how the legislative change affected the political experience of the candidates. Given that the legislative change did not apply to elections for provincial mayors, we use those elections as a control group, in a difference-in-differences design. Our estimates show the number of parties registered increased by a margin of around 2.2 after the legislative change. The change also increased the candidates' years of accumulated political experience, particularly in the subsequent gubernatorial elections.