Policy divergence and voter polarization in a structural model of elections∗

We analyze the relation between voters’ issue preferences, the candidates’ policy positions and voter behavior, using a simple spatial model of voter preferences. The size of policy differences between the candidates affects how important the voters’ preferred policy positions are for their vote choices. Conversely, how vote choices depend on issue preferences provides information about the direction and extent of policy divergence. Based on the model, we propose a new method that simultaneously estimates the distribution of voter preferences and the extent of policy divergence between the candidates’ platforms. Using data from multiple elections, we can separate changes in the electorate’s polarization into those driven by voter radicalization and those due to increased sorting, stemming from policy divergence.