Rating Deviation

It looks like the format of the stats page just changed. It looks good for the most part, but I don't see my rating deviation anymore. Is that something I can still check?

Damn it, you're right.  Why in the world would they want to hide that stat from us?

I think they will bring it back.

I know they were planning to add back avg. time per move.

Thanks, notmtwain.  I really wish they'd stop fixing stuff that ain't broke!

The new stats have only been released to a subset of members (it had previously been beta only). They did that to get more feedback but they are working on adding things that are missing and wanted.

Thanks, Martin.  Only to a subset of members, eh?  Gosh, that makes me feel special...

Thanks! That's good to know.

Oh, I guess I'm part of the test group then. Thanks for letting me know! Perhaps this forum post is useful feedback for them.

Its horrible that a chess site would hide the mathematics behind their rating system from their members. I think this speaks volumes. I'm new here and I've suspected from day one that the rating system here is broken. Upon doing some research my suspicions were confirmed when I found out that from time to time chesscom awards free points across the board to "fix" their distribution. 

If you were to look up chess elo formula, for example, you would very quickly find it online. This might be useful for someone trying to estimate how long it will take to reach rating goals. Yet, chesscom not only starts people at random ratings based on user preferences but they insert a RD value which further skews their rating distribution and breaks it at various ranges - hence why they have to add points to members on occasion. Imagine joining the USCF and stating that you're an "expert" and should start with a rating of 1800 (arbitrary number). How do you think people picking their starting rating from various options would affect the distribution?? Rhetorical. 

Let's not forget that chesscom recently merged time controls causing more chaos. What a mess. Link below.

https://www.chess.com/news/view/10-minute-chess-now-rapid-rated-bullet-ratings-increased

https://www.chess.com/blog/rishabh11great/the-chess-com-rating-system-has-changed

I don't think they are hiding the mathematics so much as assuming most users won't be interested in the full formula. Their basic description of the rating system is very sparse on details, but it also contains links to more detailed posts at the bottom. One of those posts links to Glickman's paper on the Glicko system. If you're interested in the details, I recommend checking those out. The RD value does appear to be completely hidden at the moment, and I really hope they change that. I don't see any reason why we shouldn't have access to it.

Glicko is a widely used rating system and the RD value is designed to handle uncertainty in ratings based on a lack of recent performance data for a player in games from any given pool. There's nothing wrong with the rating system.

US Chess uses a different system designed by the same person, and they occasionally go through an adjustment to the system to fight inflation/deflation as well, so making adjustments isn't, in and of itself, necessarily an issue with the rating system. US Chess also uses initialization formulas to come up with an initial estimate for players that have never played before, for something to use in the initial rating formulas.

The RD value still shows on the apps, but for many people, the RD value is just confusing to some people, but the use of it does what it's supposed to do.

More than a year later, the RD display remains missing. Looks like it was intentional, for some odd reason. I wonder if it has anything to do with speedrun accounts.

I imagine it's just that most people don't really understand what it is so was removed from view.

If you use the public API, the data is still viewable that way.

Thanks for bringing that to my attention! For the RD, we can go to this link (replace username with your own username):

https://api.chess.com/pub/player/{username}/stats

And more general information can be found here:

https://www.chess.com/news/view/published-data-api