It might be more fun to see users who’s emdash usage increased after the release.

HN is burying my comments (thanks!) but here it is: https://news.ycombinator.com/item?id=45073287

Maybe the HN crowd is the wrong group for such statistics, a higher percentage here probably knows how to use their keyboard and OS.

Although note — people are likely to be infuenced by the recent prevalence of em dash to use it more in their own writing nowadays

Agreed.

More generally any measurable feature of writing that underwent a significant change in frequency around that time would be interesting to look at. Looking at frequencies across the entire post dataset would suggest likely candidates, which individual people could then be tested against. There would be lots of confounding factors and red herrings though -- like the word "ChatGPT" itself!

Even more interesting is the likely increase in emdash usage by those not using an LLM, but merely imitating the writing they see subconsciously. There was a evidence that chatgpt is shifting the frequency of use of some uncommon words and phrases amongst non-users.

I missed the point of the leaderboards completely. It is to show exactly that when you get blamed for using AI to write. You can point out that you already used it in 2009 or whatever. For that it is very useful yes :-)