District magnitude, economic performance, and party-system fragmentation in five Latin American countries

This article makes a fresh start in the attempt to explain the number of parties in patty systems. It develops a simultaneous equations model to differentiate between the psychological and mechanical effects of district magnitude on party-system fragmentation. Both effects are statistically significant and approximately equal. However, neither effect is very large in comparison to underlying patterns of politicization, which are argued to be reflections of the number of political cleavages in society. These cleavages predispose each party system to converge toward a country-specific effective number of parties within 5 elections, regardless of the initial level of fragmentation, barring outside disturbances. Major devaluations may act as such disturbances, but the evidence so far is inconclusive. The analysis is based on new data f3rom 62 elections in Argentina, Bolivia, Colombia, Peru, and Venezuela, supplemented by 30+ additional elections in Brazil, Chile, Costa Rica, Ecuador, Mexico, and Uruguay for the exploration of economic impacts.