I think the 13k default rank is doing harm [Closed]

[meili_yinhua]

@flovo

To balance 3 entry points in a way that prevents inflation/deflation would be a real hassle.

I’ve just gotta say that even Glicko-2 doesn’t do this. In fact Glicko-2 is not a zero-sum rating system like ELO is, therefore the average rating of all rated players can (and often does) shift up and down as time progresses. The single-point average of Glicko is nothing more than an arbitrary point which is a relic of ELO ratings.

However, it has been shown to the devs to be more accurate (at least on a pure % wins standpoint) than not doing so, so they chose to follow Glickman’s original implementation in order to follow that.

Although their implementation of the ratings period is not 100% perfect
as shown by this quote from flovo where he modified some of OGS’s rating period system to more accurately correct for the current ratings (although he only took his own games and the test is inconclusive):

Flovo's analysis

@flovo

I’ve first estimations.
I used the opponent ratings as provided by OGS (no recalculation of their rating history).
I only recalculated my rating history with OGS like Glicko2 (again with opponent ratings provided by OGS).

rms is calculated over (outcome - win_probability)
direct % as 1 - Σ(outcome XOR player_rating > opponent_rating) / number_of_games
(outcome = 1 if player win, and outcome = 0 if opponent_win

Prediction quality of my rating history: (rms: lower is better, direct %: bigger is better)
Player id: 449941
Games: 978

algorithm	rms	direct %
OGS	0.4645	64.93%
Glicko2	0.4637	65.95%

There is no difference in predictability.

To get the right values for Glicko2, I would have to recalculate the histories for the whole player base. At the moment I’m not able to do that (rating history gets cropped to max 5000 games).

EDIT: Forgot to adjust ratings for handicap games in the calculation of the direct %. Now both are slightly higher.

It is worth mentioning that it may be more accurate to have people seeded in at the overall site’s average (or maybe even just the average for players with a low enough deviation), but that would probably be for little gain (and might even be for a loss).