Presidential election polling numbers continue to emerge regarding Brazil’s President Luiz Inácio Lula da Silva (Lula) and Flávio Bolsonaro.
A late-September poll by Indexa and Broadcast showed different margins in the first round and the runoff.
Looking at both the final-week polling and the actual vote count from the 2022 presidential election also reveals why poll numbers are difficult to read directly as election results.
3-Line Summary
1. Lula led the first round in the Indexa poll
2. The hypothetical runoff was 43% to 42%
3. Polls reflect respondents’ views at the time of the survey, not the result
First Round: 39% to 34%; Runoff Within the Margin of Error
In an Indexa·Broadcast poll reported by CartaCapital, Lula received 39% and Flávio Bolsonaro 34% in a hypothetical first-round matchup. The gap between the two candidates was 5% points. The poll was conducted by interviewing 2 thousand people from September 27 to 29, and the margin of error was plus or minus 2.2% points.
In the same poll, the hypothetical runoff matchup between the two candidates showed Lula at 43% and Flávio Bolsonaro at 42%. The 1% point difference fell within the stated margin of error, so the report described it as a technical tie. The key point in these figures is that leading in the first round does not mean the same margin of advantage in the runoff.
The poll also included other runoff scenarios. Lula led Romeu Zema by 43% to 36% and Ronaldo Caiado by 43% to 40%. The matchup against Renan Santos was 44% to 38%, while the matchup against Augusto Cury was 41% to 39%. However, all of these were responses to hypothetical choices presented by the polling organization, not actual voting results.
In 2022, the Final Polls and the Vote Count Differed
InfoMoney summarized that major polls immediately before the first round in 2022 showed Lula with a relatively large lead. In the Genial/Quaest poll released on September 28, Lula was at 46% and Jair Bolsonaro at 33%; in the Datafolha poll released on September 30, the figure was 48% to 34% among all respondents.
However, the vote count on October 2 showed Lula at 48.43% and Jair Bolsonaro at 43.20%. The final gap was 5.23% points. In particular, Bolsonaro’s actual vote share was higher than the 34% recorded in the final Datafolha poll.
What this comparison demonstrates is not grounds to conclude definitively that a particular poll was wrong, but rather that polls show the distribution of responses at the time they were collected. In this poll as well, it is more important to distinguish between the first-round figures, the runoff figures, the margin of error, and the shares of nonresponse, blank, and invalid responses than to look at just one number.
References
Tags #BrazilianPresidentialElection #BrazilPolling #PresidentialElectionPolling #Lula #FlavioBolsonaro #Lula da Silva #Indexa #Broadcast #RunoffElection #FirstRound #TechnicalTie #2022BrazilianPresidentialElection