pax

02-09-2004, 02:01 PM

I have a suggestion that I may have mentioned before.

Is it possible to implement the Glicko calculations such that ratings are updated after every game? That is, instead of using the last published rating for every rating calculation in a period, you instead keep track of updated ratings and use the "current rating" for each calculation.

I believe this is the way Glicko is intended to be calculated, and indeed the way it is calculated on FICS.

This method of calculation is one way of avoiding the large swings in rating that can occur due to the time between lists. E.g if you have a number of poor performances throughout a rating list, you will lose points based on your initial high rating for each game you play. If ratings are recalculated after each game, then losses later in the list will be lower due to the reduction in rating that has already occurred (argument also holds for increases in rating due to prolonged good performance).

In order for this to work, you ideally need some "time" information in order to place the games in order for processing. The best result would be if games are sequenced individually, but I realize it may not be possible to extract separate date info for each game. Sequencing can be done on a tournament by tournament basis - it may lead to slightly inaccurate ordering (for example if people are playing weekly in one tournament and also in a weekender), but this would still be better than the present batch processing.

Processing the games this way would definitely take longer, but should still be feasible.

The main downside is that it becomes more difficult for people to estimate their rating change through a period, since they don't know what rating will be used for their opponent in a particular game. This isn't a big deal at the moment however, since any calculation is approximate unless you know everybody's RD and volatility precisely.

Any thoughts on this approach in principle?

Pax

p.s

Come to think of it, the pronciple difficulty is probably getting tournament organisers to submit their results punctually. When tournaments are submitted months late, this would obviously mess with the system. Still, it messes with the system as it stands in any case.

Is it possible to implement the Glicko calculations such that ratings are updated after every game? That is, instead of using the last published rating for every rating calculation in a period, you instead keep track of updated ratings and use the "current rating" for each calculation.

I believe this is the way Glicko is intended to be calculated, and indeed the way it is calculated on FICS.

This method of calculation is one way of avoiding the large swings in rating that can occur due to the time between lists. E.g if you have a number of poor performances throughout a rating list, you will lose points based on your initial high rating for each game you play. If ratings are recalculated after each game, then losses later in the list will be lower due to the reduction in rating that has already occurred (argument also holds for increases in rating due to prolonged good performance).

In order for this to work, you ideally need some "time" information in order to place the games in order for processing. The best result would be if games are sequenced individually, but I realize it may not be possible to extract separate date info for each game. Sequencing can be done on a tournament by tournament basis - it may lead to slightly inaccurate ordering (for example if people are playing weekly in one tournament and also in a weekender), but this would still be better than the present batch processing.

Processing the games this way would definitely take longer, but should still be feasible.

The main downside is that it becomes more difficult for people to estimate their rating change through a period, since they don't know what rating will be used for their opponent in a particular game. This isn't a big deal at the moment however, since any calculation is approximate unless you know everybody's RD and volatility precisely.

Any thoughts on this approach in principle?

Pax

p.s

Come to think of it, the pronciple difficulty is probably getting tournament organisers to submit their results punctually. When tournaments are submitted months late, this would obviously mess with the system. Still, it messes with the system as it stands in any case.