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  1. #1
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    The 400 point rating steal...

    Would it be possible please for a list to be posted of all the players who have had 400 points arbitrarily removed from their rating by the ACF?
    Thanks in advance...

  2. #2
    Monster of the deep Kevin Bonham's Avatar
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    Quote Originally Posted by GTB333 View Post
    Would it be possible please for a list to be posted of all the players who have had 400 points arbitrarily removed from their rating by the ACF?
    Thanks in advance...
    No, the forum does not allow the posting of messages less than two characters long.

    Perhaps you could give a few examples of players who you think this has happened to?
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  3. #3
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    Me. Geoff Butler. I lost 2 games out of 7 (with a beer at my side during the ‘tournament’) and was docked 425 points for returning to competitive chess. 2069 to 1644.
    I also believe Liam Ryan.
    Don’t follow the modern version of Australian Chess that closely, but if I know two, then I bet there’s more!
    Thanks for responding... look forward to your info...

  4. #4
    Monster of the deep Kevin Bonham's Avatar
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    Quote Originally Posted by GTB333 View Post
    Me. Geoff Butler. I lost 2 games out of 7 (with a beer at my side during the ‘tournament’) and was docked 425 points for returning to competitive chess. 2069 to 1644.
    Your rating was 2067 as of March 2007. Between then and the June 2014 ratings period you lost 41 points as a result of minor system-wide adjustments that, when made, result in previous rating lists being rerun for everybody.

    As of March 2014 your rating was 2026?? After playing one tournament it dropped 385 points to 1641?? It has since risen 3 points without playing as a result of system-wide adjustments.

    Liam Ryan's case is similar - he played in one ratings period after being inactive for about eight years and dropped over 300 points. There have indeed been several other similar cases.

    This is contentious sometimes but not arbitrary - it is the way the Glicko system's mathematics (ACF uses a modified version of Glicko-2) responds to players who are long inactive. When they return it doesn't scrub their old ratings altogether, but it treats them as very unreliable and is much more interested in their new data. If their performance on return is much weaker or stronger than their old rating then their new rating will be much closer to the new performance and not to their old rating. If a player returns after being long inactive and their first result on return is much stronger than their old rating they can gain hundreds of points.

    There are good reasons for all this. A player who has not played for a long time and suddenly returns may be a former weak junior who has been playing online and has since become a strong adult - it makes no sense for them to be severely underrated for years, dragged down by their old rating. Alternatively, an older adult who returns has a fair chance of being rusty and below their former strength, or they may be a senior player who is simply not as strong as they used to be. It makes no sense for such a player to be overrated. Especially (a problem with the Elo system) senior players shouldn't be able to maintain active ratings that are unrepresentatively high by coming out of the woodwork for a single interclub game every couple of years.

    There are, however, cases where the returning player just has a bad tournament first up or is rusty for a few tournaments before returning to their former strength. In these cases, because the system flags their rating as unreliable, it will quickly correct its assumptions as they play more games and show that they are as good as they used to be or better. Here's one example - the returning player was initially very rusty and dropped 250 points in a few tournaments, but very soon regained them all and more:

    http://www.bjcox.com/wp-content/plug...=2000&eyr=2017

    But when the only data the system has for someone in 13 years is one tournament where they were drinking, it's hard for it to know how good they are!
    Last edited by Kevin Bonham; 14-03-2020 at 09:19 PM.
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