Personal or Partisan Incumbency Advantage? Evidence from an Electoral Reform at the Local Level in Italy

We analyze the incumbency advantage using a large data set on Italian municipal elections held from 1993 to 2011. We first apply a non-parametric Sharp Regression Discontinuity Design comparing parties that barely win an election to those that barely lose, exploiting the fact that partisan incumbency status changes discontinuously at the threshold of margin of victory of zero. In order to disentangle the personal incumbency advantage from the partisan effect, we rely on a reform that introduced mayoral term limit, and exploit the exogenous change on the incumbency status of mayors keeping the partisan incumbency status constant. We find that the incumbency advantage is essentially driven by the personal effect. The results are robust to different specifications and estimation strategies with excellent balance in observable characteristics. Also, the effect of interest is larger in magnitude for municipalities located in the South of Italy compared to northern municipalities.