The Electoral Sweet Spot: Low-Magnitude Proportional Electoral Systems

摘要

Can electoral rules be designed to achieve political ideals such as accurate representation of voter preferences and accountable governments? The academic literature commonly divides electoral systems into two types, majoritarian and proportional, and implies a straightforward trade-off by which having more of an ideal that a majoritarian system provides means giving up an equal measure of what proportional representation (PR) delivers. We posit that these trade-offs are better characterized as nonlinear and that one can gain most of the advantages attributed to PR, while sacrificing less of those attributed to majoritarian elections, by maintaining district magnitudes in the low to moderate range. We test this intuition against data from 609 elections in 81 countries between 1945 and 2006. Electoral systems that use low-magnitude multimember districts produce disproportionality indices almost on par with those of pure PR systems while limiting party system fragmentation and producing simpler government coalitions.