by PublicABCP
Translated and reviewed by Matheus Lucas Hebling
The article “Pesquisas eleitorais e mudanças tardias na decisão do voto” examines the discrepancies between electoral polls and actual election outcomes. The study, conducted by Frederico Batista Pereira, Assistant Professor of Political Science at the University of North Carolina, and Felipe Nunes, Professor of Political Science at the Federal University of Minas Gerais (UFMG), investigates the hypothesis that a portion of the electorate changes its voting preference between the final week of the campaign and election day.
The authors carried out an online experiment during the week leading up to the first round of the 2022 presidential election. In the experiment, voters who were not aligned with either Lula (PT) or Bolsonaro (PL) were shown short campaign videos from Lula. According to the authors, if late changes were rare, these videos would have little to no persuasive effect.
In addition, models of undecided voter allocation and strategic (or “useful”) voting, grounded in political science theory, were applied to a pre-election poll conducted shortly before the first round. These models aimed to test the applicability of vote-switching theories in the Brazilian context.
The results revealed that a significant portion of participants remained open to changing their vote during the final week. Specifically, 8% of voters who watched Lula’s campaign videos considered switching their vote to him, and 7% changed their vote immediately, compared to the control group.
Voters most likely to change their preference were those who were undecided or initially supported third-party candidates, as opposed to those intending to cast blank or null votes or to abstain.
The study suggests that exposure to campaign messaging in the final days can meaningfully influence vote decisions. The authors argue that polling institutes and analysts should take this factor into serious consideration.
About the Authors
Frederico Batista Pereira is an Assistant Professor of Political Science and Public Administration at the University of North Carolina and a member of the institution’s Latin American Studies Programme. He holds a PhD and Master’s in Political Science from Vanderbilt University and also earned a Master’s in Political Science and a Bachelor’s in Social Sciences from the Federal University of Minas Gerais.
Felipe Nunes holds a PhD in Political Science and a Master’s in Statistics from the University of California, Los Angeles (UCLA). He is a Professor of Political Communication, Elections, and Methodology at the Federal University of Minas Gerais (UFMG), and Director of both the Centre for Legislative Studies (CEL) and the International Centre for Public Management and Development (CIGPD).
Publication Details
Title: Electoral Polling and Late Changes in Vote Choice
Authors: Frederico Batista Pereira and Felipe Nunes
Year of Publication: 2024
Read more in: Opinião Pública – Vol. 30, No. 1
