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All comments by Ping Hu
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@Steve,

I completely agree with you on #1. Notice the plot of rating vs. masterpoint. There were almost no players landed in the region of low rating but high MP. I speculate those high MP players mainly played in club where they still could get masterpoints, and stopped playing in tournament. Using rating to organize tournament could enable them to come back to tournament.

Single player rating might be able to derive from individual game but we don't have a lot of games of that type. In absence of any direct measure, you have to derive from pair data. I've thought of defining single player rating by selecting his/her most active partnerships and weigh their rating by time. This might be useful in estimate two players (as pair) initial rating.

I'm not quite sure I understand your matrix. When kind of data got feed into the matrix. At first look it seems you try to use it to convert between single player rating and pair rating, but then it does not look that is what you want to do when you talked about 173000x173000 matrix.
Nov. 16
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I believe this is in response to a District 6 request from the following thread.
https://bridgewinners.com/article/view/is-this-a-way-to-run-an-organization/
Nov. 8
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The current board members are listed below. Eight of them term ended in 2020. I suppose no new DD will be elected after that.
https://www.acbl.org/about-acbl/administration/board-of-directors/
Nov. 5
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Jan,

I also use 3 to show the other major, not necessarily . It asks opener to respond if he/she has 3 cards in the other major. Do you think if this is comparable?
Nov. 4
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I have the counts for board 8 below. I think this one is clearly favoring EW if you compare with score sheet.

ns_score ew_score counts
NP NP 4
1100 -1100 2
800 -800 4
500 -500 10
430 -430 16
420 -420 22
400 -400 39
300 -300 8
250 -250 2
200 -200 15
180 -180 3
170 -170 25
150 -150 20
140 -140 179
110 -110 122
100 -100 25
50 -50 15
PASS PASS 3
-50 50 408
-90 90 4
-100 100 356
-110 110 2
-150 150 87
-200 200 13
-250 250 6
-470 470 1
Nov. 2
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@Howard, here is the board 1 results I pulled from ACBL database. There are 4 no plays.The other scores go from -500 to 530 for NS. I don't have a score sheet and could not compare them.

ns_scr ew_scr counts
NP NP 4
-500 500 8
-490 490 1
-470 470 1
-420 420 2
-400 400 2
-300 300 18
-200 200 2
-180 180 1
-170 170 8
-150 150 22
-140 140 101
-120 120 6
-110 110 8
-100 100 101
-90 90 1
-50 50 217
50 -50 131
90 -90 6
100 -100 70
110 -110 355
120 -120 4
140 -140 245
150 -150 10
170 -170 20
200 -200 11
250 -250 3
280 -280 1
300 -300 22
380 -380 1
420 -420 2
430 -430 1
470 -470 2
500 -500 3
530 -530 2
Nov. 2
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5 has a better chance.
Nov. 1
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I suggested you to use Power Rating to search for new partner next time and let us know what your experience is.

I have tried it once during NABC. I found a player with 55% power rating thinking he should be reasonably good. When I discussed with him what conventions to use, I found he only knew about the basic ones like Stayman, Transfer and Blackwood. He did not even know Exclusive RKB. It happened that on one board we really need it and I made a wrong guess on what Ace he had.

My experience may not be common but I would like to hear others.

No matter what, I think you agree a rating system is better than current masterpoint.
Oct. 30
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Chess players seems to be comfortable with the same complex formulae. I think the issue is about rating itself. Players only want to see something working. No many of them know the details.

Bridge rating needs to have some time to be accepted. The experience of EBU NGS could give us a clue what might happen.
Oct. 30
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@John, Clubs running Commongame have their player ratings in Commongame data base. It has beening running for over four years.

When I first developed my system Chris Champion and I had tried to compare results from same set of game files. Our results had some differences. We know they would be different because he only uses the game score and I use board results. I'm not very familiar with his methodology to know if he derives individual rating from pair ratings or vice versa.

If you are intersted in your rating, PM me and I'll send you some files.
Oct. 27
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@Robert, if a pro only plays with one client I double any rating system to distinguish who is a better player. Power rating also needs you to play at least 3 different partners. If you play with multiple clients and your clients also play with other partners, it is not difficult to figure out who is better.

The problem with individual rating is I could not find a way to determine/measure it objectively. This does not means that it is not possible to define/derive some “individual rating” from pair rating for any specific purpose. The things I could come up to measure individual player are looking at their declarer play of the same contract, and the results on defense when the player is opening leader. However these only measures a specific skill. If you want to know who is a better player in a partnership, just look at the scores when each one is declarer.

The last question you ask is why we need such a rating system when we've already had a Power Rating and NGS. Certainly this depends on what you are going to use it for. With other rating system you probably could get a good estimate on a player's strength. However it I want to get handicap on board basis, it is not possible (Power rating only use game level data so the handicap is for entire game). In commongame we have observed that some club game had a very strong pair, if the movement was in such a way that some pairs played against this pair, but others did not, those who didn't would have a 2% advantage over those who did. A single stregth of field factor applied to entire game, not board to board would not be able to distinguish them.

In my OP I also discussed the uncertainty of score prodiction and it implication to tournament organizer. It is well known that if you put very strong players and very weak players in the same event, no body would be happy. It would drive away the weak players. I could see this in our regional KO because it basically could not have enough teams to start a game now. The lack of high masterpoint but not high rating pairs in my OP data plot may also indicate those players stopped playing in tournament. I think one of possible solution is to bracket players by rating. In my OP the data showed if the rating spread is 240, the players expected score would be in one standard deviation. The tournament organizers could choose their own criteria, but a good rating system could provide a quantified measure to sovle their problem.

Their could be other usages I have not thought of.
Oct. 27
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@Brenda, contact L4C support about your problem. I know it could not handle USEBIO file created from my Swiss team program as well. Right now the IT department is busy to handle all different type of game from ACBLscore game file, USEBIO is not a high priority.
Oct. 27
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@Adam, if you read my reply to Richard (3rd comments of this thread), you could see in your scenario the pro expected score would be 50%.
Oct. 27
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This is a long story. I first proposed this system to ACBL in 2015. The ranking committee reviewed it but did take any action. Their interest at that time was to create a couple of new masterpoint ranks of Ruby and Sapphire to keep people playing.

When Bahar was CEO, Chris Champion and I got e-mail from him and it seemed we could have some study but we never had a concrete plan. Furthermore I think Bahar had some idea of his own to rating individual players based on how they play certain boards. After his abrupt departure, nothing happened.

From my point of view, ACBL has known different rating system for years. Chris had maintained his system for years. However my system needs board result and that data was never available to me. So MP committee would have an interest to see results from my system when they want to decide some kind of measures for Strength Of Field.

As to how a rating system could affect on players, there are several EBU players have said their NGS had generated a lot of interest from players and did not see a large amount of players stop playing as some people speculated.
Oct. 25
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I think you are asking to see the data used in making 3D histogram. If you are interested PM me and give me your e-mail, I could send you the file.

Here I just give you some numbers for expected score of 45-46% (could not find a good way to insert a table).
Actual Scores | Counts
40-41 856
41-42 981
42-43 1088
43-44 1143
44-45 1244
45-46 1231
46-47 1163
47-48 1189
48-49 1099
49-50 993
Oct. 25
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Masterpoint Committee is interested in this study. They are considering to award masterpoint based on strength of field.
Oct. 25
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In my early study I have included Gold Rush and other NLM events. You could found them in my technical note from Commongame website.

For this study asked by BOD Bridge Committee they are only interested in Open games.
Oct. 25
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No. Online tournaments and some other special tournaments like cruise are not included.
Oct. 25
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My understanding of NGS is that it uses weighted results of players for a fixed period of time. So even you don't play, your rating could change over time.

Elo methodology is different. All your past results are reflected in current rating. If you don't play it does not change. In Chess rating there is also a “floor”. If a player reach certain level, he would have a floor that his rating would never drop below it. The “floor” raises as player's highest rating reaches a new level.
Oct. 25
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@Jeff, give you a quick update. I tried to filter on the date range to see how the mean value would change. It does move the value. I tried most recent 2.5 years and 1 year and the mean value went from original 0.38 to 0.36 then 0.34.

I also tried to filter on only players with less than 200 boards and the mean value changed -0.33%. This confirms it is a bias introduced by data selection.
Oct. 24
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