I wrote something for the Economist Game Theory blog on the controversy in the US Open women’s final. Here’s one part I hope people remember:
The tennis world will probably be debating Mr Ramos’s calls until the next major rolls around in January. But one thing should not be in doubt: Ms Osaka didn’t need his help to earn her first grand slam title. Excluding the five penalty-determined points, she won 60 of the 110 points played, good for 64% on her own service and 45% on return. A ratio of that quality almost guarantees victory. In addition, all five of the points Ms Williams was docked would have been played on Ms Osaka’s serve. Given the level that the 20-year-old sustained, the first point penalty increased her chances of winning by less than half a percentage point, from 97.8% to 98.2%. Even if Ms Williams had been able to raise her level to equal her opponent’s, the impact would have been less than two percentage points. The game penalty was worth barely a full percentage point, boosting Ms Osaka’s probability of victory from 98.1% to 99.2%. By the time the New York crowd started booing, the match was virtually in the bag.