11/05/2022

Viana comments on the 'predictability' of football, in a column in Folha.

Rio de Janeiro – Seleção brasileira de futebol feminino disputa semifinal com a Suécia, no Maracanã (Fernando Frazão/Agência Brasil)

Reproduction of Marcelo Viana's column in Folha de S. Paulo.

In 2010, American statistician Nate Silver, who had become famous for using mathematics to predict the results of baseball games and the election of Barack Obama , was asked to analyze the World Cup in South Africa. He predicted that Brazil would be champion. We lost 2-1 in the quarterfinals and finished in sixth place.

There was nothing wrong with Silver's math, which, incidentally, wasn't any worse than other experts': it's just that soccer is much more difficult to model mathematically than other sports. According to researchers at Cornell University in the United States, the favorite team wins in only 50% of cases, while this happens 60% of the time in baseball, and almost 70% in basketball or American football.

This is scientifically explained by the Law of Large Numbers, a theorem about random events like coin tosses, proven in 1713 by the Swiss mathematician Jacob Bernoulli. The law states that, although the outcome—heads or tails—of each toss is unpredictable, if repeated many times it is practically certain that each side will come up half the time: the probability of having more than 51% heads or tails is very low.

A basketball game consists of a large number of plays in which teams try to score points. Success is uncertain with each play, but with repetition the stronger team eventually prevails. In soccer, however, there are few moments likely to alter the score: it is rare to have more than a dozen shots on goal. Thus, the result is much more random: Cornell researchers estimate it to be 50% talent and 50% luck.

Some believe it's unfair that the best team is subject to losing simply due to bad luck. The problem could be "solved," they say, by changing the rules to increase the number of goals per game, which would reduce the role of chance.

But unpredictability is precisely one of the aspects of football that makes it so captivating: in what other sport could the North Macedonian fans enter the stadium hoping to eliminate the four-time champion Italy?

Moreover, in sports like baseball and basketball in the United States, great efforts are made to keep the teams balanced and, in doing so, restore the role of luck!

To read the full text, visit the newspaper's website.