In another thread, Kirby wrote:Mef wrote:Generally for a rating system, accuracy is the ability to correctly predict the outcome of a game between two players. To that end KGS does very well, especially compared to most other systems.
KGS does well, assuming that someone has an unchanging rank. If someone is 5k, and they're going to be 5k forever, then the maximum likelihood approach correctly uses history to estimate a rank. If someone is improving, KGS does not do so well compared to some of the other online systems, because past history makes it such that playing a lot of games makes it harder to adjust your rank, even if you have genuinely improved.
While it's true that KGS can do well with players that are not improving (or declining in skill), it is misleading to say that it universally does a good job of correctly predicting game outcome, when other systems that are not weighted so heavily by the history of past games do better in some circumstances.
Case in point: If KGS were accurate, people would not be inclined to create new accounts just to get a correct rank. We see this happen on a regular basis.
I keep seeing claims that the KGS rank system encourages users to create new accounts in order to get a more accurate rank. But, I wonder how well this belief is justified?
As a player, not as an admin, I have seen a few users create new accounts because they think they deserve a higher rank. At first, they actually do get a higher rank. But, after several ranked games with the new account, their rank stabilizes to what it was with the previous account. The rank graph shows only a tiny, if any, difference.
However, my experience is very limited here. The few cases I have seen are insufficient for me to conclude the premise that creating a new account to get a more accurate rank is false. As an admin, I have seen several users who are "account abandoners" but I have not investigated to see if they change accounts in order to obtain improved ranks. Furthermore, those with the most accounts have the fewest ranked games in each of their accounts, and the number of ranked games in these accounts is too few to draw conclusions that changing accounts gives them a rank that is both higher and stable.
Yes, the KGS rank system does take into account all ranked games played in the last six months. However, the weight of a game result decays exponentially, so recent games have more influence on users' ranks.
In short, I do not believe the claim that the KGS rank system encourages users to make new accounts in order to get a higher rank. But, my experience is insufficient to decide either way.
If one does have a stable rank with a large history of ranked games and one does think one's rank should be different, I think it would be better to try to play games with handicaps that reflect what one thinks one's rank should be. For example, if you think you should be one stone better, as Black, take one fewer stone in handicap, or offer one more as White.
As was said in the other thread, the KGS rank system is not intended to correspond with rank systems elsewhere. It is intended to help users find fairly matched games.