The Spatial Organization of Elections and the Cube Law

Abstract

The single-member district plurality system for legislative elections, also known as first-past-the-post (FPTP), usually results in disproportional seat distributions among parties. The Cube Law which stipulates that the ratio of seats won by the parties in a two-party system is a cubic function of the corresponding rat to of total votes, attests to the degree of disproportionality in representation under FFTP This so-called law, however is really just a benchmark, and the performance of FPTP can vary from country to country and from time to time.\nIt is well known that the validity of the Cube Law, and hence the proportionality of representation, depends on the distribution of vote share across constituencies. Scholars have painted to contagion, heterogeneity, and the size of constituencies as factors that may affect the conditions under which the Cube Law can be sustained. In this article, we propose a spatial regression model which implies all these factors. Empirically, we investigate Taiwan`s recent legislative elections to test our theory. Our findings show that, in this case, law spatial autocorrelation at the district level is associated with vastly disproportional election outcomes.