Anatomy of a Black Swan? Explaining the 2018 Italian Election Result through a Novel Issue Voting Model of Voter Transitions

The recent Italian general election has been regarded as historical, leading to what has been labelled as the first «populist» victory in a large West European country. However, this election fits in a more general Western European trend with similar characteristics. In a context of remarkably high volatility, challenger parties have proven successful by often proposing innovative, ideologically cross-cutting issue packages, exploiting a relatively low level of ideological structuring of the electorate. In this paper, we investigate the importance of issues in determining the electoral result in Italy. We rely on the Italian data of the Issue Competition Comparative Project dataset. These country-specific innovative computer-assisted web interviewing surveys, designed to allow comprehensive testing of issue-voting theories, include a very large number of issues, with measures of issue preference for positional issues, and, for both positional and valence issues, measures of party credibility and issue priority. Based on these data, we implement a novel approach for explaining the electoral result. We estimate models of voter transitions from and to various parties based on party-voter affinity in terms of party credibility and issue priority. We are able to assess the specific issues that were relevant in explaining the electoral successes and failures of different parties, thus constructing an integrated explanatory model of the overall electoral result.