Rating Deviation

Hello community, I would like to ask question about rating deviation, as I don't understand it much. I know what are the things it causes, of course.

But anyway, there is one not named player, who is playing only 1500? rated players in 1/2+0 TC. Currently he is riding 170+ winning streak. His rating is going only slowly up, same as his placement in leaderboard. But his Rating deviation is now 46,76.

Isn't there some coding of RD that prevents you from climbing leaderboard with decling equal opponents and farming provisionally rated beginners?

Can anybody explain me how does this work?

Thanks in advance.

Regards, Kex.

@Kex09 He is lowering his deviation because for all we know, these people he's playing could be 2200 strength on a new account and they are giving him the benefit of the doubt.

It seems to me that if a person plays with weak players and gains rating, there is nothing wrong with that. He plays for fun and as you know you can play with anyone. It doesn't matter, even if a player has not played a single game with a rating higher than 1500, even in this case there is nothing to worry about.

@EN-J0Y It is not meant as offence and sorry if you took it that way. I am just wondering how does it work, because there were already GOAT-s like Bruheimo and Teilchen who reached 2600+ rating in this way and never appeared on leaderboard as their rating deviation never dropped below 75 or so.

Having fun on lichess is #1 priority for me and my projects also. This forum thread is more to increase my knowledge. =)

From Wikipedia:

"The RD measures the accuracy of a player's rating, with one RD being equal to one standard deviation. For example, a player with a rating of 1500 and an RD of 50 has a real strength between 1400 and 1600 (two standard deviations from 1500) with 95% confidence. Twice (exact: 1.96) the RD is added and subtracted from their rating to calculate this range. After a game, the amount the rating changes depends on the RD: the change is smaller when the player's RD is low (since their rating is already considered accurate), and also when their opponent's RD is high (since the opponent's true rating is not well known, so little information is being gained). The RD itself decreases after playing a game, but it will increase slowly over time of inactivity."

Bruheimo plays only low rated players which cannot decrease RD much (because of a big difference in elo which exists in the Glicko's formulas) nor he plays very often. On the other hand, 1/2+0 players can give so much games very fast which easily drop RD below the Lichess limit for leaderships.

@arimakat Thanks for explanation Vlad!

So if I understand correctly, 1/2+0 TC gives a lot of games and also decreases RD by decimals. So it is possible to reach lower RD just to big amount of games?

Yes, there is a formula that decreases the RD after every game. So if you play a lot of games against decent players you can reach a low RD very fast. Lichess also has a lower limit which is RD=45, so you cannot go below 45 and players who regularly play has RD between 45 and 50. However, the mentioned formula depends on the rating difference, so in a case of big difference your decreasing will not be fast enough (Bruheimo case).

What is the best Rating deviation?

On lichess it's 45 I think. I could be wrong, but from my understanding, I've never seen someone dip below 45.00