Where Do Parties Live? Electoral Institutions, Party Incentives, and the Dimensionality of Politics

Objectives This study examines how electoral systems shape the underlying dimensionality of political discourse by incentivizing certain strategies among parties. Methods Cross-sectional linear regression is used to examine how electoral systems affect dimensionality. The study provides an original measure of dimensionality derived from an empirical estimation of a spatial model of voter preferences over political parties. Data are from the Comparative Study of Electoral Systems. Results The analysis indicates that electoral institutions strongly affect a nation's dimensionality, especially in socioethnically homogenous countries. Less proportional electoral systems engender a unidimensional political space. Results are robust across several model specifications. Conclusions Individuals and the media conceptualize government and ideology in dimensional terms. Moreover, much academic work assumes certain dimensional constructs. By testing theoretical predictions about electoral systems and political dimensionality, this study provides an empirical basis for such assumptions.