Even though runoff elections are the most common form of presidential elections in the world, voter-choice behavior in these two-round elections have not received the attention they deserve in the literature. Two-round elections provide political consultants and candidates with rich and factual data on voter preferences, revealed through the voting behavior observed in the first round, which can guide the planning and implementation of their final campaign. They also allow political analysts to apply their voter-choice models to actual voting behavior (rather than voting intentions) in a multi-party election during the first round, and validate their predictions in a two-party election in the final round. I use results from the four most recent Brazilian presidential elections to demonstrate how voter-choice models can be applied to guide political campaigns in runoff elections.
