Abstract
How often will elections end in landslides? What is the probability for
a head-to-head race? Analyzing ballot results from several large
countries rather anomalous and yet unexplained distributions have been
observed. We identify tactical voting as the driving ingredient for the
anomalies and introduce a model to study its effect on plurality
elections, characterized by the relative strength of the feedback from
polls and the pairwise interaction between individuals in the society.
With this model it becomes possible to explain the polarization of votes
between two candidates, understand the small margin of victories
frequently observed for different elections, and analyze the polls'
impact in American, Canadian, and Brazilian ballots. Moreover, the model
reproduces, quantitatively, the distribution of votes obtained in the
Brazilian mayor elections with two, three, and four candidates.
