Complexity in the European party space: Exploring dimensionality with experts

Does the n-issue space in domestic European polities reduce to one, two, or more dimensions? How do these dimensions relate to each other? More broadly, how does dimensionality vary across countries? We attempt to advance our understanding of political contestation in Europe by mapping the dimensionality of the political space across 24 countries using Chapel Hill expert survey (CHES) data. We test how well different models of the European political space fit the CHES data and find that three-dimensional models best fit the data in all countries. However, there is considerable cross-national variation in how the three dimensions relate to one another. Given this, we present a new measure of dimensional complexity that captures the degree to which these three dimensions are related. In so doing, we improve our understanding of the complexity of the political space in European countries.