There is a discussion on Hacker News, but feel free to comment here as well.
In the study, 1,000,000 patients were treated by a male surgeon, and 100,000 treated by a female surgeon.
That’s quite the discrepancy. Doesn’t explain the results, but it does show that there were far more male surgeons than female. Which might mean that there is a selection bias somewhere in the process.
Lots more to study.
Having on one side the top 1,000,000 male surgeons and on the other side the top 100,000 female surgeons makes a difference, which is really hard to measure. Of course both are not the top surgeons, but it is just harder to find more of a kind. Imagine looking for 100,000,000 male surgeons, which is probably impossible given the education demographic in the US.