Effects of the representation system on the distribution of votes and seats in Latin America (1990–2019)

One of the main consequences of the legal rules that govern electoral systems is that theyestablish the conditions for the conversion of votes into seats. Based on various public sourcesof information, this essay constructs indicators on the effects of the rules adopted in the electoralsystems of Latin America in the period 1990-2019 in terms of the fragmentation of votes andseats.The evidence analyzed shows that there is no defined and constant pattern that reflectsthat the adoption of a proportional representation system results in a different fragmentationthan that which occurs when a mixed system is available. The lower fragmentation of the votethan of seats does not turn out to be a product of the presence of partisan alliances. Thefragmentation of voting in mixed systems has increased systematically, a situation that does notoccur in the case of proportional systems.