Separate ratings between board sizes

[shinuito]

@shamisen

The decision to merge all the ratings was apparently made by a ~15 kyu player with this logic:

Maybe look a bit further.

The most recent decision I remember was

@anoek

Does it make sense to continue counting 9x9, 13x13, and 19x19 games toward the same overall rank like we do?

@anoek

From this data there’s two things to note:

1. Using a combined rating works quite well, certainly comparable or better than looking at per-size strengths by themselves. It seems to me like it makes sense to keep using it.
2. Using overall ratings to predict 9x9 games works pretty good at HC 0 and at HC 1, indicating to me that the strength bands are pretty compatible with 19x19 or just “go ranks” in general. However, going beyond HC 1, predictions start to get bad pretty quick. I believe this is an indication that the “Old Japanese Recommendation” is not so great for us, and that we should strongly consider figuring out what the best 9x9 (and probably 13x13) handicap setup should be.

EDIT: The question arose about considering blitz vs live vs correspondence ranks, here’s the data from that, which I believe is still very supportive of using an overall rank for picking handicap.

It’s not just a random decision, there’s data to support that it works (or worked) just as well or better than the individual ratings at predicting who would win in a matchup.

Now I think it can be fair to ask for another up to date analysis, or to suggest other methods of testing whether the overall rank works better than then individual. That seems reasonable to me.

@shamisen

Ratings for 9x9 should never be mixed with 19x19 under ANY circumstances. They are almost separate board games. Of course getting stronger in one would lead to getting slightly stronger than the other, but the same can be said about switching between Chess and Go. Players who are good at one board game usually reach a similar ELO rating in the other game without too much effort, from what I’ve seen.

I don’t think this is very accurate. It wouldn’t take much effort to get a 9x9 rank to match your 19x19 rank because they’re very similar games, they have very similar tactics, reading, life and death, endgame, tesuji. You’ll have to adjust things slightly for the board size sure, but the skill set is very similar.

Chess is not very like Go at all, and I’m pretty sure it would take a lot of effort for people to match their Go rating in Chess unless they weren’t that highly rated.