Does MMM-MMP Difference Matter? Mixed Systems and the Size of Government.

The increasing use of mixed-member electoral systems has led to an explosion of research attempting to specify their effects. Understanding mixed-member system 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 on size of government has found that government expenditures are positively correlated with electoral system proportionality. Our statistical analysis of government expenditures in eighteen mixed-member systems between 1985 and 2002 shows that MMP systems, which are more proportional than MMM, are correlated with higher levels of government spending. Thus, the MMM-MMP distinction has clear policy implications [ABSTRACT FROM AUTHOR]