Join Bridge Winners
All comments by Ping Hu
You are ignoring the author of this comment. Click to temporarily show the comment.
Robin,

I discussed with Chris Champion and had compared our rating results with him on some sample data. My understanding is his rating is mostly based on most recent 18 months games. EBU system has a predefined weighting that favors recent results.

My system has a built in weighting. After a tournament, the players rating is adjusted by their performance. So the final rating is determined by two factor. First is their pre-event rating. Second is their performance. You could think of pre-rating as a weight of all their past games. The performance adjustment is current weighting. The performance adjustment is scaled by a K factor. It depends on how many games the players have played and how many boards from current tournament. It also depends on players' rating. Lower rated players get a large K value. For master level players the adjustment is usually very small. This is similar to chess rating system. K factor could be fine tuned. USCF has its rating system for 70 years, but still adjusted their K factor formula two years ago.

As you pointed out, volatility is not good for rating system. It needs to have some stability. I think the Elo methodology is sound in principle. Bridge score could be handled better than chess. In chess the game result only has win, loss and draw. In each tournament, a player only plays 4 or 5 games. So the results are very limited. If a player gets all wins or all losses, their rating could be changed a lot. In bridge, you rarely see a score of 24 IMP, in MP most of the games are between 40-60 % and each time players would play 20-30 boards. So bridge score could provide better statistics than chess. My system differs from others because I calculate based on board results. Others mostly use overall result from a game of 20-30 boards. In my case, I could find out exactly who played the same board and what their ratings are. In other systems they could only make an average adjustment for field strength. This affects on rating result of how fast you could reach a pair's “true” rating.

In my example from 2005 Bermuda Bowl, I calculated rating after each round results. For highest rated pair Norberto Bocchi and Giorgio Duboin, their rating after first round they played was 2706 (from 20 board result). After that it varied to a low of 2607 and high of 2763. After 200 board, it was 2727. At the end of tournament (476 boards) it is at 2714.
April 11, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
There are a few ways to deal with initial rating assignment. If most of the pairs in a tournament already have ratings and the new pair played at least 15 boards against rated pairs, I calculate an estimate based on the score and average opponent rating and use it to calculate rating. If most of the pairs are unrated, I used a default initial rating. This default could be different based on type of event. In my Bermuda Bowl calculation, I used a default rating of 2400 that is appropriate for masters. For club open game, I would chose 1300 (average player's rating). For a limited game, I may chose a lower number like 1100.
April 10, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Yes, there are always same kind of luck in bridge. However when you compare a large amount of boards, statistically it should average out. This is just like play an 8 boards match, stronger team may not always win. However they are much more likely to win with 64 board match.
As I explained about the methodology, there are at least 4 pairs that could affect on one rating calculation. If the board is flat or one player acts irrationally it could create some problems. However not every board will be like that and we have to assume players will act rationally. The only board I would throw out is the one with adjusted scores(like the game won by forfeit in chess).
April 10, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
A rating system is not a replacement of masterpoint. Masterpoint is about reward and players want to get rewarded for their play. The problem is using masterpoint to determine what flight/stratum a player should play is not accurate. A player would eventually pushed up to a flight/stratum beyond his ability. This could only hurt player's continue participation of game because he/she has no chance of winning.
A rating system that measures player's ability used in pairing would put player in a group of similar playing strength. It could encourage players to play more by creating a better playing environment. So even a player with a lot of masterpoint could continue to play against players of his strength and not forced to against stronger players.
April 10, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Does EBU use per board result or just overall percentage and average of field strength?
April 10, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
This is basically a pair-team format. I saw a number of sectional/regional tournament using it. The score was calculation for MP in pair and BAM in team. However you could certainly create other combinations like cross IMP for pair and VP for team.
March 27, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
As I said early there is a condition this kind of problem could happen. In order to avoid it, 6 rounds of Swiss team needs to have 12 or more teams.
March 24, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Masterpoint is just a marketing tools for ACBL. It is like giving candy or toys to kids as reward. For old people you give them masterpoints.
Instead of looking at how much an event pays masterpoint or how much masterpoints a player has, maybe we should advertise by masterpoints per dollar and use masterpoints/dollar to evaluate how good a player is.
March 23, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
This pairing problem in Swiss team could happen any time when number of teams are less than twice of number of rounds. In chess pairing director needs to “look ahead” in anticipate future round of pairing problem. I don't know know if ACBL TD has similar training or not. However Swiss pairing in bridge has more ways to solve this problem. For example, it could make 3-way pairing in 2nd to the last round and make sure all teams with a shot to 1st place would play each other.
March 23, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
This depends on seeding program. In general it takes time to enter player data into computer, but it is easy/quick to remove a player. Even early entry is not 100%, a rough estimate of size could help in determine number of sections and how to balance the players.
March 21, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Adam is correct. We need incentive for early entries. This is regularly done in chess tournament where early entry gets 20-30% discount than at the door entry fee.
March 21, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Seeding could be done with computers. It does not need two hours.
March 21, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
The root cause is in ACBLscore. It only keeps information about who played against whom for pair game and BAM, not for Swiss team and KO.
March 19, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
I also got a result that I played in a junior event with someone I don't know.
March 15, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Mike, there is a simple solution to your problem. ACBL just needs more senior only events where it allows limited conventions. Let the Open event really OPEN.
March 9, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Greg, could you share some of your “proposal going forward”? Maybe the readers here could help with “some unanswered questions”.
March 8, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
So we could allow some destructive bids like preempt, DONT and some other convention calls against NT and strong club, but not others.

By the way I like to play Precision and would be very happy if we could outlaw all destructive calls after 1 open, so I could make my bid without interference.
March 6, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
Is preempt constructive or destructive?
March 6, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
I saw ACBL posted a Technology Committee minutes for 2/27. Anyone know more details about the item on ACBLscore+?
http://www.acbl.org/acbl-content/wp-content/uploads/2015/01/Technology-Minutes-02-27-2015.pdf
March 5, 2015
You are ignoring the author of this comment. Click to temporarily show the comment.
I started to learn bridge in late 1970s, then absent from game for about 20 years before returning it in late 90s. When I first came back, I found there were a lot of new conventions. There were Bergen raise, jump shift were weak instead of strong. At that time it would be easy for me to say it was best to play like 20 years ago when there were not so many conventions. I had to learn and adapt.

The solution I think should not be restriction but full disclosure. The current convention card ACBL uses is inadequate to make a full disclosure of a system. Alert chart could only catch part of them. In a lot of cases, you need to know opponent's treatment of certain type of hands and what a bid denies. If you play on BBO, you could load a CC that has all details of every bid/sequence. Perhaps we need something like that in future tournament. Let's say we have an electronic “bidding box”. You could click on an opponent bid and find its meaning, or every player has a screen that automatically shows the meaning of opponent's bid.
March 5, 2015
.

Bottom Home Top