Glicka RD

larrycurlymoe
[COMMENT DELETED]
Metastable

It's a measure of confidence on your rating number, which is only an estimate of your actual playing strength. A high RD means your actual strength may within a large range of the number you currently have. A small RD means your true strength is probably much closer to the number you currently have.

http://www.chess.com/article/view/chess-ratings---how-they-work