2021 Rating and rank adjustments

I like rank clipped to 9d and 25k because it’s pretty.


I have split part of the discussion from here into: A separate ranking pool for children?

As it seemed to deserve its own topic.

This thread is already massive enough, please try to stay on topic and consider creating a new thread if you have any related idea.

If I have moved or deteled something you think belongs here, I appologize, please simply repeat your point again.

Many thanks.


Does anyone have a good idea why ratings changed? Ranks are understandable. But I lost 150 rating points, maybe. Is it because ratings are more stable (fixed volatility bug), and now they don’t push each other apart as much, so they bunched up towards average a little?

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my suspicion is exactly that, a bit like cooling down a fluid: when all the particles/players are moving less quickly and bumping into each other less the volume contracts


Hi, this may no longer be an issue, but I thought I’ll ask to get a confirmation, just to be sure.
btw, This is not a big deal, no urgency whatsoever. I do hope this gets cleared up eventually.

on the first day when this adjustment came live, I “created” a custom game, and restricted my opponent’s ranking. say, I only wanted to play with one of the 12k players, I specified the min and max rankings in the set up. To my surprise, a 6k was able to accept it. I suppose there’s a logical explanation for that, but it’s a bit confusing. I haven’t tried it since, so I don’t know if a 6k can still accept a 12k game, I hope not.

could you please advise what is the proper way to set up these rank-restriction games under the new system? Thanks.

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But those other dan players will also have had their ranks similarly changed, so if they were 1d when you were 4k and you are now 1d, they will be (around) 5d, so they will still have to give you handicap stones and still find it (approximately) just as hard to beat you.

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I compared the European Go Database records for some well-known British Go Association players with their new OGS ranks and the OGS ranks look a bit inflated. However, I note BHydden’s answer regarding proposed changes at the EGF.

Andrew Simons/Uberdude:


Matt Marsh/marshmn:


Gerry Gavigan/gerrysw11


Sandy Taylor/afar


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Andrew didn’t play any rated game on that acount for 7 years and Sandy only played 6 rated games on that account in the past 7 years. So those two may not be the best examples.

After the coming EGD update, Matt’s EGF rating will have fluctuated around 2k in the last 3 years. His new OGS rating has fluctuated around 1k OGS in that same period.

After the coming EGD update, Gerry’s EGF rating will have fluctuated around 10k for the last 4 years. His new OGS rating has fluctuated around 6k in that same period.

Here is a different case where is used some estimate from play quality:

From this small number of anecdotal cases, the following rough comparison table between new EGF ranks and new OGS ranks can be made:

---  ---
 1k   2k 
 4k  ~6k
~5k   9k
 6k  10k 
 7k ~10k
 9k ~15k

This may seem “wrong” for players who are used to EGF ranks, but a similar comparison table between new OGS ranks and AGA ranks may show a different picture.

I think that the data acquired from the recent rank linking feature was used to fit the new OGS ranks somewhere between EGF ranks and AGA ranks.


Edited: The other ranks are derived as 1 rank = 1 handicap and all handicap games giving about the same winrate for black (for games where black+handicap is within one around white.

The alignment at 1d is visible in your comparison table. Why it diverges at lower ranks I don’t know.


Oh, I’m a little bit surpised by that, because 1 stone handicap is basically just komi advantage for black (worth only half a move).
So when there is a full rank difference, white has an advantage when black gets only 1 stone handicap. Around 1d, I’d expect a 57/43 winning chance for white.

I now remember that this came up before: 2020 Rating and rank tweaks and analysis - #97 by gennan. But it seems that OGS was not convinced by arguments made by me and @KillerDucky in that discussion.


Wild update. I got bumped 4 stones from 9k to 5k… My AGA rank based on tournament play has been around a 9k for a while now, so wonder if the new rating system is better calibrated for stronger players?


Yes this is a big oversight if what @flovo said is correct. Why did OGS decide to come up with a completely new standard for 1 rank difference?

If you want ranks to be separated by no-komi handicap then you should do it the IGS way with 4K and 4K+.

It shouldn’t be possible for every OGS rank to be 50/50 in no komi and also be accurate for 2stone-9stone handicap games.


To clarify we didn’t target 50/50, we targeted consistency. That turned out to be about 43% as you’d expect, that was a natural number that emerged though and not something that was explicitly targeted.

But because we targeted consistency for multiple handicap levels, that changed the bend of the curve so to speak, which is why our lower ranks don’t align with the current EGF’s lower ranks (note those are subject to change as they are working on that too, I’m very curious to see how things look after their adjustments).

Right now I’m questioning my sanity a little bit though because intuitively since the EGF black win rate decreases as the handicap stones increase, that would seemingly imply that black needs more handicap stones, so the ranks need to be farther apart, which is the opposite of where the data and simulations led me with this rank update. I think I need more coffee to think that one through again, I’ve rationalized myself into circles a few times on that topic.

On the topic of handicap 1 being worth about half a stone, we did run simulations with considering hc1 as worth half a stone, but honestly it didn’t seem to make much of a difference - if anything it seemed a little negative in the results, but it seemed pretty close to noise to really say. Because of that I just kept with the current “one rank difference is one stone” for the sake of simplicity and ease of communicating that to players.


Right. The graphs show that so it was just just some confusion from flovo. I also forgot that 2-9 stone games are also technically 1.5-8.5 stones games so they should also be in that 43% which is about where the new ranking system should line up. At least until 6 stones.

There was probably a reason that KGS didn’t allow ranked games to be higher than 6 stones though - things get so inconsistent there. Handicap games are also so rare that trying to make high handicap fit a curve probably isn’t worthwhile either.


Does this make you feel any better?


Makes sense, because EGF tournaments quite often (but not always) use MMS-1 for determining handicaps, not the rank difference itself. MMS’s of course change during the tournament, so rank differences become less important as the tournament progress into later rounds.

Also since many egf tournaments are rather small, there is often a situation where the lowest ranked player(s) have already played with everyone within their handicap range before the last round(s) of tournament, so they will have to play outside their hc-range.
(For some weird reason, i feel that almost every egf tournament will have at least one 8k vs 20k game with 9hc on the final round of the tournament xD)

In short, handicap data of egf is bit dubious and should be taken with pinch of salt. I dont know how gennan analysed the data and how well he took those into calculation, but i assume there there is some natural inconsistency because different egf tournaments use slightly different rules regarding handicaps.


To clarify, when I say I’m looking at handicap games I say I look at handicap games where the handicap is supposedly appropriate given the rank difference, so in tournaments or meetups or whatever, if a handicap game is played that doesn’t align with their rank difference, that game isn’t considered for the purpose of looking at the win rates.


Just want to express how nice it is to lose 3 games in a row and not go down 3 ranks!
I also like the change to the rank table on the profile page, with kyu/dan ranks.


But doesnt that mean that you’re disregarding ton of data from egf tournaments? Or are you cherrypicking those results where rank difference matches with handicaps?


Please don’t get stuck in an infinite while loop :heart: :wink: