[Al_U_Card]

mike777, on Sep 7 2005, 03:39 PM, said:

Blofeld, on Sep 7 2005, 03:08 PM, said:

The two advantages to opening aggressively in the majors more than in the minors (that I can see) are:
1) 1M is more preemptive than 1m. We knew this already.
2) Hands with major length are more likely to have a game on with the same HCP strength. We also knew this already (as a matter of common sense), but these data help to quantify the effect. So passing on the borderline minor hands has less risk of missing a game than on the same hands with majors instead.

But is this not a function of majors being higher ranked and needing only 10 tricks. Again I see no evidence that an aggressive one level minor suit cannot be a very effective preempt affect at the one level. Virtually as much if not the same as a major. I see no reason to not open one level minors aggressively based on any of this data, can someone clue me in? thanks in advance.

Were they not referring to game producing potential? Unless the suit rank is considered and the higher ranking suit(s) get more bang for their buck?

[EricK]

Is this a reasonable question:

Given each particular hand shape, how many points are required so that the chance of game is above some particular threshold? (But what threshold?)

Will this give you some idea of how much more you need to open a minor suit hand than a major suit hand?

Eric

[mike777]

awm, on Sep 7 2005, 03:46 PM, said:

mike777, on Sep 7 2005, 02:48 PM, said:

Ok, how do you conclude this? Why is it better to open aggressively with length in majors compared to minors? I assume there are just as many advantages to opening agrressively in the minors, how does this refute that in favor of the majors? We all know it takes one less trick in the majors but so what? The chance for game in 8 or 9 card major is almost always greater than the same in a minor with same number of cards, so what?

I see the data but I do not see this conclusion, can anyone help?

There are some underlying assumptions here I may not have mentioned. Perhaps the main question is: why should I open the bidding, as opposed to passing? Some reasons:

(1) If I think we might have a game, I should bid so we can reach that game.

(2) In order to get in the opponents' way, to make it harder for them to find a contract.

(3) If I think we can make a partscore, perhaps I should open so we can get there.

(4) In order to help partner on defense, to find the right lead, count my pattern, etc.

All of these are perfectly fair reasons for bidding. But assuming fairly "constructive" methods, it seems like (1) is the major reason for opening at the one level. Keep in mind that one-level bids don't steal a huge amount of space from the opponents. Of course, things change a little bit in 3rd seat (where 3 and 4 become bigger concerns) and in 4th.

Note that many systems seem to base an opening bid on "I have half what we need for game." We see this with Goren (26 hcp for game, 13 to open), with LTC (14 losers for major suit game, 7 losers to open), and with ZAR (52 for game, 26 to open). All of these seem to be working on the assumption that (1) is the major reason to open.

So if we're willing to assume that the main reason for opening is to find our games, it seems like an opening should announce that game is reasonably likely given opener's hand. This is really what the methods above are going for isn't it? So that seems to support opening lighter with major suit length.

To give a simple example, suppose I am deciding whether to open a balanced eleven count in first seat. Since I'm balanced, directing a lead from partner (condition 4) isn't a big deal. Since I play fairly standard methods, my opening on any (4432) pattern will be one of a minor, which doesn't really take any space from the opponents. So the only real concern here is, what do I think are our chances at game? It seems from Tysen's data that it might be reasonable for me to open a 4-4-2-3 eleven count, but that with a 2-3-4-4 eleven I should probably pass.

Excellent post, very well written.

You have shifted the debate to the more important question. Why do we open?
You have listed 4 excellent reasons and stated there may be other good reasons.

Here are a couple more reasons off the top of my head.
5) opening lite makes balancing decisions easier, why, because we do not have to balance, we have told our story.

6) Not only are we making it harder for the opp to bid their contracts (2) but it can be quite exhausting to have active opp bidding. This takes time and energy away from their declarer and defensive play.

For sake of discussion let's agree reason number one, constructive bidding, is the most important.

Of course agreeing it is the most important does not mean it is of overriding importance. How much constructive bidding are we losing compared to the gain for the other reasons. By adding up several other reasons their combined importance may conclude we should open minors or 11 hcp balanced hands aggressively.

Bottom line I do not see the data answering this difficult question.

[mike777]

Al_U_Card, on Sep 7 2005, 03:47 PM, said:

mike777, on Sep 7 2005, 03:39 PM, said:

Blofeld, on Sep 7 2005, 03:08 PM, said:

The two advantages to opening aggressively in the majors more than in the minors (that I can see) are:
1) 1M is more preemptive than 1m. We knew this already.
2) Hands with major length are more likely to have a game on with the same HCP strength. We also knew this already (as a matter of common sense), but these data help to quantify the effect. So passing on the borderline minor hands has less risk of missing a game than on the same hands with majors instead.

But is this not a function of majors being higher ranked and needing only 10 tricks. Again I see no evidence that an aggressive one level minor suit cannot be a very effective preempt affect at the one level. Virtually as much if not the same as a major. I see no reason to not open one level minors aggressively based on any of this data, can someone clue me in? thanks in advance.

Were they not referring to game producing potential? Unless the suit rank is considered and the higher ranking suit(s) get more bang for their buck?

I repeat this is a function of suits needing only 10 tricks for game, so what? What is the new point?

[tysen2k]

Okay here is a more complete list:

Shape   Game?    Error
2-2=5-4  24%     0.3%
3-2=4-4  24%     0.2%
3-3=4-3  25%     0.2%
4-3=3-3  25%     0.2%
3-2=5-3  26%     0.2%
4-2=4-3  26%     0.1%
3-3=5-2  27%     0.2%
4-3=4-2  27%     0.1%
2-2=6-3  27%     0.4%
4-4=3-2  28%     0.2%
3-2=6-2  28%     0.3%
4-2=5-2  28%     0.2%
5-2=3-3  28%     0.2%
5-3=3-2  28%     0.2%
5-2=4-2  29%     0.2%
3-1=5-4  29%     0.3%
2-2=7-2  29%  *  0.7%
2-1=6-4  30%     0.4%
2-1=5-5  30%  *  0.5%
4-1=4-4  31%     0.3%
3-1=6-3  31%     0.4%
5-4=2-2  31%     0.3%
2-1=7-3  32%  *  0.7%
4-1=5-3  32%     0.3%
3-3=6-1  32%  *  0.5%
6-2=3-2  32%     0.3%
6-3=2-2  33%     0.4%
4-3=5-1  33%     0.3%
5-1=4-3  34%     0.3%
2-2=8-1  34%  *  2.2%
3-1=7-2  34%  *  0.7%
4-4=4-1  34%     0.3%
5-3=4-1  35%     0.3%
3-2=7-1  35%  *  0.7%
4-2=6-1  35%     0.5%
4-1=6-2  35%     0.4%
5-4=3-1  37%     0.3%
2-1=8-2  37%  *  1.6%
6-1=3-3  37%  *  0.5%
6-3=3-1  38%     0.4%
5-2=5-1  38%     0.4%
7-2=2-2  38%  *  0.8%
1-1=6-5  38%  *  1.2%
5-1=5-2  39%     0.4%
3-0=5-5  39%  *  1.1%
6-1=4-2  40%     0.5%
1-1=7-4  40%  *  1.7%
6-2=4-1  41%     0.5%
3-0=6-4  41%  *  0.9%
4-0=5-4  42%  *  0.6%
6-4=2-1  43%     0.5%
4-0=6-3  43%  *  0.9%
3-0=7-3  43%  *  1.4%
7-2=3-1  43%  *  0.7%
7-1=3-2  43%  *  0.7%
5-5=2-1  43%  *  0.6%
7-3=2-1  44%  *  0.8%
5-0=4-4  44%  *  0.9%
4-1=7-1  44%  *  1.2%
3-3=7-0  44%  *  2.0%
4-4=5-0  45%  *  0.9%
3-1=8-1  45%  *  2.1%
2-0=7-4  45%  *  1.7%
2-0=6-5  45%  *  1.3%
4-3=6-0  45%  *  0.9%
5-0=5-3  46%  *  0.8%
1-1=8-3  46%  *  2.9%
3-0=8-2  47%  *  3.1%
5-3=5-0  48%  *  0.8%
5-1=6-1  48%  *  0.9%
5-4=4-0  49%  *  0.7%
2-0=8-3  50%  *  3.1%
6-0=4-3  50%  *  0.9%
6-3=4-0  51%  *  0.9%
4-2=7-0  51%  *  1.7%
3-2=8-0  51%  *  3.2%
6-1=5-1  51%  *  0.9%
8-1=2-2  52%  *  2.2%
4-0=7-2  52%  *  1.7%
5-5=3-0  52%  *  1.1%
6-4=3-0  52%  *  0.9%
8-2=2-1  53%  *  1.7%
5-2=6-0  53%  *  1.3%
7-0=3-3  54%  *  1.9%
5-0=6-2  55%  *  1.3%
1-0=7-5  55%  *  3.0%
6-2=5-0  56%  *  1.3%
7-3=3-0  57%  *  1.4%
6-0=5-2  57%  *  1.3%
7-1=4-1  57%  *  1.2%
4-1=8-0  57%  *  4.6%
1-0=6-6  58%  *  3.7%
6-5=1-1  58%  *  1.2%
7-4=1-1  59%  *  1.6%
4-0=8-1  59%  *  4.7%
7-0=4-2  60%  *  1.7%
7-2=4-0  60%  *  1.7%
8-0=3-2  60%  *  3.1%
8-1=3-1  61%  *  2.1%
6-5=2-0  61%  *  1.2%
1-0=8-4  63%  *  4.7%
7-4=2-0  63%  *  1.6%
8-2=3-0  63%  *  3.0%
5-0=7-1  64%  *  2.8%
8-3=1-1  65%  *  2.7%
5-1=7-0  65%  *  3.0%
8-3=2-0  67%  *  2.9%
6-1=6-0  70%  *  2.5%
7-0=5-1  70%  *  2.8%
6-0=6-1  71%  *  2.4%
7-5=1-0  72%  *  2.9%
8-0=4-1  73%  *  4.3%
7-1=5-0  73%  *  2.8%
8-1=4-0  74%  *  4.0%
8-4=1-0  75%  *  4.3%
6-6=1-0  83%  *  3.1%

If there is a "*" that means the error is more than 0.5% and so the value should be looked at with a grain of salt.

Look at some of the ones that were excluded before. 2-2=7-2 stands out like a sore thumb. It rarely produces a game and is worse than all 4441 shapes.

[tysen2k]

mike777, on Sep 7 2005, 01:08 PM, said:

I repeat this is a function of suits needing only 10 tricks for game, so what? What is the new point?

Is that not enough? Maybe the question would be easier to answer if you asked "Why do we pass?" rather than "Why do we open?"?

Tysen

[cherdano]

In the Zar thread, someone gave a link to Richard Pavlicek's database of bridge deals with precomputed double dummy results, and I think Tysen has been using a similar database here.

Is there any reasonably big deal database that includes single dummy results, computed by one of the strong bridge programs (GIB, Jack)? I am wondering whether double dummy analysis might, for example, systematically undervalue Queens.

Arend

[awm]

There are some general issues about designing a hand evaluation method that perhaps we can try to answer by analyzing play in top competition. Here are some of them:

Is bidding double-dummy contracts good?

It's quite possible to construct hands where a contract makes double-dummy, but where no one would legitimately make the hand. On the other hand, it's easy to imagine contracts that should be defeated double dummy, but where the defense can easily go wrong. If either of these situations is too common, it would tend to indicate that there's not much value in trying to find the double dummy contract as often as possible (which would seem to be the goal of all the various hand evaluation analysis). So here are two tests we could try:

When a contract is bid in top-flight competition, how often does the result of the hand (making versus not making, ignoring extra over/under tricks) match the double dummy prediction?

If a pair were to somehow bid only the contracts that make double dummy, and always take the double dummy number of tricks, how many IMPs would they win (or lose!) when compared to real players?

Should we aim for making, or for par?

First let me define par. The par spot is the lowest contract such that neither side can improve their results by bidding more (assuming double dummy play/defense). So if no one is vulnerable, we can make 4♥, and the opponents can make 2♠, then the par spot is 4♠X by opponents, 300 for us. The various bidding analysis tend to assume that the goal is to find the making spot, not the par. The exception to this is rules like the Law of Total Tricks (and Lawrence's substitute in "fought the law"). These rules seem to perform poorly when compared to things like zar/bumrap/binky points, but they're really aiming for a different target. So here are the questions:

How often does the par result involve my side going down in a contract?

If a pair were to let their opponents bid and make their best contract rather than competing to the par spot (when par is negative for their side), how many imps per board would they lose?

If these numbers are large, it suggests that aiming for the making spot might be the wrong idea. Note that I expect these numbers to depend a lot on vulnerability -- when unfavorable it will rarely be right to bid something that will not make.

Is there an advantage to overcompeting par?

In principle there could be advantages to overcompeting par. For example, suppose I open 3♠ on a hand where the opponents cannot make a four-level contract. It may be the case that 3♠ doubled will go two down for -300. So it's a bad bid... or is it? It could well be that the opponents have great difficulty doubling the contract, and will often be pushed into a bad 4♥ game. If I had passed they would have played 3♥ making three. So how can we measure this?

Examine hands from top flight competition where one side bid beyond par. Compare their actual result on the board to the par result (computed using a double dummy solver). How many IMPs did they gain/lose on these hands?

[mike777]

Yes,
1) should hand evaluation measures get us to the best possible contract or the best contract possible?
2) should hand evaluation measures be an important tool in resolving conflicting goals such as getting us to the best contract or not giving the opp a free ride to theirs?

Please note these goals are different from getting us to the PAR spot or to the best contract.

I just played a TM. We lost on this hand. Ok we could have won it on another hand that involved hand evaulation but that one did not involve me. This hand I had the crucial decision to make. I decided that we could not make 3nt on any normal lead or defense so did not bid it. Our opp bid it and made it on a lead that I thought as obviously not best on the bidding. How do we factor that into hand evaluation?

If you set junky goals you get junky results. On the other hand a new bidding tool or theory need not be perfect, just better, whatever that means.

[Echognome]

As a follow-up to this, I would find it quite interesting if there was another column. Namely if for each shape there was %chance WE make game and %chance OPPS make game. This might help when discussing whether or not it's important to get into the auction.

[PMetsch]

awm, on Sep 7 2005, 07:51 PM, said:

There are some general issues about designing a hand evaluation method that perhaps we can try to answer by analyzing play in top competition. Here are some of them:

Here are some conclusions from a Peter Cheung. He has done a lot of statistical work (also with OKbridge data). All the numbers can be found at:

http://crystalwebsit...d.com/index.htm

I am no expert, so I can not tell if all those numbers make sense.

Quote

Is bidding double-dummy contracts good?

copied from double dummy accurate section

The most important general finding is that double dummy analysis is very accurate as compared to actual play from OKBridge. The overall total number of tricks taken by the declarer is 9.21 (9.22 for imp and 9.20 for mp). The double dummy analysis of the same deal produce 9.11 (9.12 for imp and 9.11 for mp). So actual play by OKBridge player takes 0.1 tricks more then the double dummy analysis result. This is from 383,000 deals and over 25 million plays.

Quote

Should we aim for making, or for par?

copied from final contract section

Out of 25 non-slam contracts only 8 contracts are shown to have positive results.

They are 1H 1S 1NT 2H 2S 3NT 4H 4S. This is the case for both imp and mp scoring. I call them "our contracts" or "Peter's 8 contracts". If it is our hand we prefer to play in "our contract". If it is their hand, we prefer them to not play in "our contracts"

You may also be interested in data on the folowing page: http://crystalwebsit...nd_patterns.htm

[cherdano]

PMetsch, on Sep 8 2005, 11:43 AM, said:

Quote

Is bidding double-dummy contracts good?

copied from double dummy accurate section

The most important general finding is that double dummy analysis is very accurate as compared to actual play from OKBridge. The overall total number of tricks taken by the declarer is 9.21 (9.22 for imp and 9.20 for mp). The double dummy analysis of the same deal produce 9.11 (9.12 for imp and 9.11 for mp). So actual play by OKBridge player takes 0.1 tricks more then the double dummy analysis result. This is from 383,000 deals and over 25 million plays.

This information is not very important. What would be important is the typical error (e.g. by stating how often DD analysis is off by 1 or 2 or 3 tricks etc.)
By the same argument, if I throw coins and decide for 4 out of 5 deals that NS can make 9 tricks, and 10 on the other, this would be a perfect analysis for MP contracts, since the average predicted number of tricks is 9.20.

Arend

[PMetsch]

cherdano, on Sep 8 2005, 04:59 AM, said:

This information is not very important. What would be important is the typical error (e.g. by stating how often DD analysis is off by 1 or 2 or 3 tricks etc.)

Just looked at all those numbers at the website, but I could not find info about errors nor other data to calculate errors.

Another interesting point about the comparison of DD solver vs.OKBridge: The OKBridge declarer takes more tricks than the DD solver declarer. Now assume the DD solver is correct, then how can OKBridge declarer beat the best possible result? I think he must be playing worse than the DD solver, but the OKBridge defenders play much worse to compensate.

[FrancesHinden]

PMetsch, on Sep 8 2005, 04:43 AM, said:

The most important general finding is that double dummy analysis is very accurate as compared to actual play from OKBridge. The overall total number of tricks taken by the declarer is 9.21 (9.22 for imp and 9.20 for mp). The double dummy analysis of the same deal produce 9.11 (9.12 for imp and 9.11 for mp). So actual play by OKBridge player takes 0.1 tricks more then the double dummy analysis result. This is from 383,000 deals and over 25 million plays.

Surely there is a big variation by contract, and particularly by level?

I believe that I tend on average to beat DD par when declaring at the 1- and 2-level, and I am substantially worse than DD par in slams.

Also, I would expect 3NT contracts to be close to DD par when bid after the defence has opened the bidding (becuase the opening lead is likely to be right, and because everyone knows all the high cards).

[PMetsch]

FrancesHinden, on Sep 8 2005, 07:00 AM, said:

Surely there is a big variation by contract, and particularly by level?

copied from:

http://crystalwebsit...my_accurate.htm

The following table is a break down of the numbers by the level for NT contact.                       
actual play  double dummy    difference

level 1       7.34      6.93      0.41

level 2       7.86      7.56      0.30

level 3       9.29      9.10      0.19

level 4       10.25     10.10      0.15

level 5       10.34     10.25      0.09

level 6       11.40     11.48     -0.07

level 7       12.27     12.40     -0.12


The following table is a break down of the numbers by the level for spade contact.
actual play  double dummy    difference

level 1        7.83      7.64      0.19

level 1        8.18      8.06      0.13

level 1        8.61      8.52      0.09

level 1        9.86      9.87     -0.00

level 1        10.30     10.23      0.07

level 1        11.45     11.57     -0.11

level 1        12.26     12.39     -0.12

Obvious the last table should read level 1 untill level 7

Quote

I believe that I tend on average to beat DD par when declaring at the 1- and 2-level, and I am substantially worse than DD par in slams.

If the data above is true then you are not the only one . At higher levels the defense make less errors/wrong leads.

[Fluffy]

Nice data, your data base is fully randomly generated?, and how much time did it take to analyse all those deals double dummy?

[tysen2k]

Fluffy, on Sep 8 2005, 06:51 AM, said:

Nice data, your data base is fully randomly generated?, and how much time did it take to analyse all those deals double dummy?

The database is 1 million random deals that Matt Ginsberg compiled using GIB. The database is available on his website. I don't know how long it took him to generate them all.

[tysen2k]

Echognome, on Sep 8 2005, 12:03 AM, said:

As a follow-up to this, I would find it quite interesting if there was another column.  Namely if for each shape there was %chance WE make game and %chance OPPS make game.  This might help when discussing whether or not it's important to get into the auction.

I was thinking about this yesterday too. On my list.

[han]

Exactly Matt, I was thinking the same thing. For example, with 2344 shape I expect that the opponents are more likely to have game than with 4432 shape. This could be a reason for opening with the 2344 shape as well.

Also, I expect that the more unbalanced we are, the more likely the opponents have game (since they are more likely to have distributional hands too). This could be yet another argument for opening light with highly distributional hands.

BTW thanks for adding the freaky hands too. Now that we have the errors available too, we can draw our own conclusions from these.

[han]

cherdano, on Sep 8 2005, 04:59 AM, said:

By the same argument, if I throw coins and decide for 4 out of 5 deals that NS can make 9 tricks, and 10 on the other, this would be a perfect analysis for MP contracts, since the average predicted number of tricks is 9.20.

Arend

Arend,

This is very disturbing to me. Last time I was in Germany they were using Euros, and these coins have only two sides. It seems to me that it is impossible to guarantee a 4/5 chance by throwing coins a finite number of times.

Apologies for an off-subject response.