[noticias.uol.com.br] reported that Brazil’s Quaest polling institute released a survey on October 3 ahead of the first round of the 2024 presidential election, estimating former President Luiz Inácio Lula da Silva (PT) at 46% of valid votes and Flávio Bolsonaro (PL) at 45%. The calculation relies on a “likely voter model,” a method used globally to estimate turnout and adjust poll results accordingly.
How the Likely Voter Model Works
The model combines two factors: historical voting patterns and individual voter motivation. According to Quaest director Felipe Nunes, who explained the method in an article for The Globe, the first dimension analyzes past abstention rates across demographics like age, education, and gender. For example, 39% of voters aged 70–74 in 2022 failed to cast ballots, compared to 11% of those aged 55–59. The second dimension assesses motivation through questions about interest in the election, perceived risks, and likelihood of voting. A voter in a historically low-turnout group might still be classified as a “likely voter” if they express strong engagement.
Why the Model Matters
The likely voter model aims to refine election forecasts by accounting for the gap between declared intentions and actual participation. In 2022, Nunes noted that Lula’s margin over Bolsonaro narrowed in final polls due to higher abstention among his supporters. By weighting responses based on estimated turnout, Quaest adjusts for this discrepancy. For instance, a 40% split between two candidates could shift to 53% and 47% if one group is more likely to vote, even without changes in stated preferences.
Who Is Most Likely to Abstain?
Data from Quaest highlights disparities in turnout. Voters with lower education levels and men across most age groups tend to skip elections more frequently. Women with only a primary education and over 70 years old are among the most underrepresented in polls, according to Nunes. These patterns reflect broader trends: Brazil’s abstention rate rose from 16.8% in 2006 to 20.9% in 2022, with 32.8 million people missing the ballot.
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