Moderating Political Extremism: Single Round versus Runoff Elections under Plurality Rule
研究了单一轮次与两轮多数决选举对候选人数量和极端选民政策影响力的影响，利用意大利城市人口门槛的断点回归设计发现，两轮制下候选人更多但政策波动更小。
We compare single round versus runoff elections under plurality rule, allowing for partly endogenous party formation. Under runoff elections, the number of political candidates is larger, but the influence of extremist voters on equilibrium policy, and hence policy volatility, is smaller because the bargaining power of the political extremes is reduced compared to single round elections. The predictions on the number of candidates and on policy volatility are confirmed by evidence from a regression discontinuity design in Italy, where cities above 15,000 inhabitants elect the mayor with a runoff system, while those below hold single round elections.