Ideological and geographical patterns in European political system: An Archetypoid and Spatial Analysis

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Understanding how political parties position themselves ideologically and how party systems are structured across Europe is essential for explaining patterns of electoral competition and voter behavior, as well as for mapping their spatial and geographical dynamics across regions and countries. Using data from the Chapel Hill Expert Survey (CHES), this paper applies Archetypoid Analysis (ADA) to describe the political landscape of European parties. ADA identifies observed parties that represent extremes in multiple policy dimensions (economic, organizational, sociocultural, and environmental), allowing each party to be expressed as a convex combination of these archetypoids. The analysis then moves to the country level, examining how national orientations reflect the composition of parliaments in terms of party seat shares. By aggregating party positions weighted by parliamentary seat shares, we derive national indices of left-, center-, and right-wing orientation. Ternary and spatial analyses reveal clear geographical regularities, with neighboring countries exhibiting similar profiles. Spatial autocorrelation tests confirm these patterns. Finally, beta regressions using principal components of the 19 CHES policy dimensions identify three underlying drivers (social conservatism/authoritarianism, neoliberalism, and extractivist nationalism) where only the first explains spatial dependence. Overall, the results highlight how both ideology and geography jointly structure the European political landscape.