摘要：What are the effects of attempts at reelection on electoral competition? We have tested the assumption that attempts at reelection have a positive and significant effect on electoral competition. We measured electoral competition using two indicators: Imbalance index T (Taagepera) and generalized concentration index (Herfindahl-Hirscham (HH)). We analyzed data on the seven last Brazilian national elections (1990-2014). We employed descriptive (variable measures and times series) and inferential statistics (regression analysis with panel data). Our main findings: 01. the percentage and the concentration of incumbents has a significant and negative effect on the concentration of votes; 02. the interaction between the percentage of incumbents in a given dispute and in a coalition has a significant and positive effect on the concentration of votes.
