Explaining the effective number of parties: Beyond the standard model

This study casts new light on the conditions determining the effective number of parties in elections. The state-of-the-art mostly considers the interaction between the permissiveness of the electoral system and social heterogeneity, labelled the standard model. This study argues that we should move beyond the standard model and also consider voters' short term ideological preferences as well as the diversity of issues on the party system agenda. Moreover, the effects of these variables are expected to be conditioned by electoral system permissiveness. The hypotheses are examined on the basis of a longitudinal dataset containing information on 696 elections that took place in 79 countries between 1945 and 2011. Importantly, the hypotheses could only be confirmed on institutionalized party systems.