ting presidents by majority run-off, individually, contribute to fractionalization. Holding and congressional elections concurrently and electing presidents by plurality contribute create less parties. In Brazil, after 1994, there have been many effective parties. Mainwaring an Shugart's Table 11.2 in Chapter 11 shows Brazil to have an average of 6.08 effective parties in the lower house and 9.5 effective parties in the upper house. Brazil has congressional elections concurrently and uses the majority runoff for presidential elections. In comparison, Brazil's 1954-1990 non-concurrent congressional elections, the average of effective parties varied from 3.9 to 5.7. This indicates other factors are influencing the outcome, like proportional representation. From 1945-1950, Brazil held congressional and presidential elections concurrently and elected the president by a plurality. Holding to Mainwaring and Shugart's hypothesis, Brazil had only 2.71 effective parties. Uruguay has a low level of effect parties. Mainwaring and Shugart's hypothesis is partly incorrect about Uruguay in respect to the district magnitude. Brazil's district magnitude ranges from 1 to 9.3. Uruguay's district magnitude is 99-almost the whole country. According to Mainwaring and Shugart's hypothesis, countries with a high district magnitude should have a high number of effective parties because they are likely to use proportional representation. Uruguay has only 2.6 effective parties. This is explained by the electoral cycle with is concurrent for congress and elects the president by plurality. Other factors, like party discipline explained later, play role. Argentina, like Uruguay, has a low number of effective parties. According o Mainwaring and Shugart's Chapter 11 table 11.2 the average number of effective parties in the Lower House is 2.62. The average in the upper house is not available. Argentina has recently changed the nature of the ele...
