How many medals will each country win in Rio at this Summer's Olympic Games? Researchers who derived predictions from two different models anticipate that the USA, China, Russia, and the UK will retain their top positions in the medals ranking, but Brazil and Japan are expected to make the biggest gains.

As described in a new Significance article, the first model primarily describes a country's medals as a function of the number of medals won at the previous Olympic Games, and the second model includes additional socio-economic variables.

"Yes, past success is a good predictor of future success in the Olympic Games, and the bigger, better-off countries are almost guaranteed to do well given the socioeconomic advantages they enjoy, but it should be remembered that a certain level of unpredictability remains in any sporting competition," the authors wrote. "The history of the Olympic Games is full of surprising performances by individual athletes, and we should expect to see more of them in Rio in August."