The future of Brazilian polling after recent mistakes

Romanian-born Andrei Roman moved to Brazil in 2006 as part of an academic exchange program, attracted by his fascination with Latin American literature and the magical realism of Gabriel García Márquez and Jorge Luis Borges. He spent around half a year in Brazil’s Northeast region, getting to know the country’s disparate realities and researching ways to battle poverty.

A political scientist and Ph.D. in government from Harvard University, he studied every Brazilian election since the country’s return to democracy in the mid-1980s, coming to the realization that domestic politics are not too far removed from the magical realism of his favorite authors. “It has all the ingredients: mania for grandeur, lust for power, betrayals, and the historical cycle that repeats itself again and again,” he says.

Years later, he and his husband Thiago Costa co-founded Atlas Intel, a data analysis company that, in the first round of this year’s presidential elections, came closer than traditional pollsters to correctly forecast the final vote result.

The company also correctly predicted the outcome of Chile’s constitutional exit referendum and this year’s elections in Colombia and France. In the 2020, website FiveThirtyEight named Atlas Intel one of the most prolific pollsters in the U.S. presidential election between Joe Biden and Donald Trump.

Ahead of the October 2 first round in Brazil, leading pollsters Datafolha, Ipec, and Quaest identified a reasonable chance of former President Luiz Inácio Lula da Silva clinching the election in a landslide. Incumbent Jair Bolsonaro, meanwhile, was expected to receive around 36 and 38 percent of valid votes.

While Lula’s 48.43 percent of votes was forecast within the margin of error of major pollsters, they missed a trick with Mr. Bolsonaro. The president surpassed all expectations and finished the first round just five points behind Lula, setting up a close-run second round on October 30.

The final Atlas poll before the vote still underestimated the president,...