Institutional Design, Ethnic Heterogeneity, and Party System Fragmentation

Taking into proper account the geographic distribution of ethnic groups and the operation of electoral systems reveals that the impact of ethnic diversity and electoral systems on the number of parties has been badly underestimated. Contrary to earlier findings, ethnic diversity spurs party proliferation in countries with both majoritarian and proportional electoral systems, though the effect is stronger in the latter. The insights gained here provide a theoretically derived measure of ethnic diversity useful for estimating its effect on specifically political phenomena and an improved holistic measure of the impact of electoral systems. More crucially, the results indicate that electoral system designers have greater capacity to structure electoral outcomes with hopeful implications for efforts to promote interethnic peace through institutional design. The results rely on multivariate models created using a new database with election results from 1990 through 2011 in 65 free democracies