Seminar series A generative theory of party systems Add to calendar 2025-11-06 17:00 2025-11-06 18:30 Europe/Rome A generative theory of party systems Seminar Room 2 Badia Fiesolana YYYY-MM-DD Print Share: Share on Facebook Share on BlueSky Share on X Share on LinkedIn Send by email Scheduled dates Nov 06 2025 17:00 - 18:30 CET Seminar Room 2, Badia Fiesolana Organised by Department of Political and Social Sciences In the context of the Comparative Politics Seminar Series, this session features a presentation by Chris Hanretty (University of London). In this event, Professor Chris Hanretty presents a generative model of party systems. For a given system size N, the model generates shares and positions of parties on an economic left-right dimension. The model first generates shares with a mean vector as described in Taagepera and Allik (2003) drawn from a Dirichlet distribution as described in Cohen and Hanretty (2024). Positions are then drawn according to four mechanisms: (1) positions weakly centred on the position of the mean voter; (2) initial bimodality of the positions of the largest party, (3) system autoregressive positions for the second-largest to the last party, whereby positions of the nth party are repelled by the share-weighted positions of all larger parties, and (4) increasing dispersion with decreasing vote share. The model is trained on data from over 300 elections. Hanretty discusses the implications of this generative model for party system congruence and for polarisation.