Differentiating Mixed-Member Electoral Systems

Abstract

The increasing use of mixed-member electoral systems has led to an explosion of research attempting to specify their effects. Yet there has been no work on the economic policy effects of such systems, even though this has been a significant subject of debate for scholars analyzing other electoral systems. An analysis of mixed-member system policy effects is problematic, given the wide variation in institutional rules among different systems. This article attempts to determine whether the institutional differences between mixed-member majoritarian (MMM) and mixed-member proportional (MMP) systems lead to differences in policy outputs. The political economy literature finds that government expenditures are positively correlated with electoral system proportionality. Our statistical analysis of government expenditures in 17 mixed-member systems between 1990 and 2000 shows that MMP systems, which are more proportional than MMM systems, are correlated with higher levels of government spending. Thus the MMM-MMP distinction produces significant policy differences.