Many Enemies, Much Honor? On the Competitiveness of Elections in Proportional Representation Systems∗

We develop a model of elections in proportional representation electoral systems in which the number of candidates running for office, and the differentiation in ideology and quality among candidates are jointly determined in equilibrium. We show that in symmetric equilibria (i) candidates invest more to increase their quality when more candidates run for office; (ii) changes in the cost of running for office or shifts in the cost of increasing quality induce a positive correlation between the equilibrium number of candidates and their investment in quality; and (iii) a less ideologically focused electorate leads to more differentiation in the policy positions represented in the election and to a smaller number of candidates running for office. We also consider equilibria with limited asymmetry among candidates, and establish a positive relation between the quality of candidates and the effective number of parties. ∗This paper was prepared for the Workshop on The Political Economy of Democracy, Barcelona, June 5-7, 2008. Mattozzi acknowledges financial support from the National Science Foundation. †Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, California 91125, USA; [email protected], [email protected]