Welcoming beginners and OGS rating system (A compendium)

[shinuito]

— partly for me becuase I’d like to be able to find these again at some point —

@anoek

You certainly can’t “just set ranks”, that was horrible when we did it for lots of reasons.

@anoek

We can’t count on users setting a good rating/rank when they join, the system needs to quickly find a suitable rating and rank for them.

Generally reading this post in regards to what’s wanted for a rating system to do on OGS is quite interesting.

Testing the Volatility: Summary

Yes we use the code in goratings/glicko2.py at master · online-go/goratings · GitHub almost verbatim, the only differences are around bindings to internal data structures and whatnot, if it’s a concern I’d be happy to send along a diff of the two versions. (I can confirm there’s no algorithmic differences in the diff, just things like we name things “v5_Glick2Entry” instead of just “Glicko2Entry”, stuff like that. Note we don’t use the gor implementation in that repository at all, that was jus…

Re:

@Groin

It has been demonstrated that we don’t need a unique entrance point for the adjustement to work.

I don’t think it’s been demonstrated sufficiently if I’m honest.

It was discussed here

Glicko-2 does not require accounts to start at 12 kyu. So why do we do that?

This topic is in response to yet another new topic in which a beginner is complaining about getting trashed by much stronger opponents and the OGS advice is to just take a few beatings to establish a rank. OGS uses the Glicko-2 rating system. This has advantages of stability, speed of response, etc. However, as has been noted multiple times on this forum, this has the restriction that new accounts start at 12 kyu, which in turn leads to the situation of beginners getting matched aga…

and @Vsotvep did some simulations

Why does "restrict rank" allow ? players?

I also looked at the math once, and at that time could not discover any reason why starting at a different rating would have impact on the overall system. However, I was not completely sure, and expected that drift may be a factor, therefore I thought to test it experimentally. I simulated 5 players in the system, assign each an initial strength (1 to 5), and let the chance of player A winning from player B equal 0.5 + arctan( strengthA - strengthB ) / π (the wider the gap in strength, the more …

but I wouldn’t call that sufficient to say how a system of millions of players might behave when only simulating the ratings of about 5, even if one “player” doing something like rating reseating etc might simulate many different players.

@Groin

for the adjustement to work.

I mean it’s probably true that the individual ratings adjustments might not care at what rank people enter at, if we focus on that point, but think of the system of a whole - what problem would you want to address and what does adding many entry points solve?

For instance if we have one set of 12kyu players that dislike playing [?] ranked players, imagine we had entry points of 1d, 5k, 10k, 15k, 20k and 25k for example, we will now likely have 6 different sets of people that will make Reddit posts saying that they don’t like playing with new players that have chosen their ranks at these entry points.

That doesn’t solve the recent Reddit post problem I don’t think for instance.