eyhung

I just ran a 1000-hand sim on this hand, computing the par score for the deal on each deal that fit the criteria (none of the other players has an opening bid or preempt, East does not have an aggressive preempt) : Average North HCP = 9.349 (theoretical average = 9.33) Average NS par score = 4.2 I imagine a great player would find opening this to be positive IMP-expectation.

If you play aggressive openers, that's fine, but then don't expect people who aren't as aggressive to draw your conclusions. My simulation opens at the 1-level if the hand fits the rule of 24 : HCP + longest two + quick tricks * 2 = 24. Not perfect but I think "good enough" for simulating lots of hands. void AJxx KQxxx xxxx is a clear 2nd seat pass to me -- you have no spades! If the opponents have 8+ spades, they are going to be able to outbid you cheaply and partner will probably misjudge what to do. If partner has enough spades to stop the opponents, your hand does not fit his and is thus worth less than it might appear -- the auction 1D 1S 2C XS seems likely and your hand doesn't have the extras to compensate for the trump void.

Got it, dellache, we agree, I missed the double-dummy qualifier.

I guess I worded that poorly. I meant that the double-dummy line in 1NT, more often than in other contracts, is not as obvious to declarer. Finding the double-dummy line to defend 1NT is even harder. Overall the defense vs 1NT suffers more than the declarer, but I still find myself taking more bad lines declaring 1NT than, say, 3NT.

That's the opposite of what I said. In general, the LOWER the contract, the MORE advantage declarer has in real-life. The article is "Declarer's 'Advantage'" by Jeff Miller in the May 2009 Bridge World. In this article he talks about his analysis of 48000+ results from 822 deals played from the Shanghai world championship. At the 1-level, declarer should make 63.2% of the time but actually makes 68.8%, for a declarer advantage of 5.6%. This advantage always decreases as level increases. At the 4-level, declarer makes 2.5% more contracts than he would make double-dummy, so if your sims say 4H makes 52.5% of the time, in reality you will make 55%. The 5-level is roughly even with double-dummy, and in the slam zone, the advantage shifts to the defense by 3-4%. His conclusion is that when you are evaluating contracts by simulation, you should adjust for declarer's advantage.

Actually, there was a recent article in the Bridge World on whether double-dummy defense / declarer play is dependent on level, and I believe its conclusions were, after analyzing expert play, that "declarer's advantage" shrinks as the level of the contract increases. You can see this most strikingly with the contract of 1NT, which is often described as the hardest to defend (and declare!). Against a major-suit game, expert defenders can achieve double-dummy defense a surprising amount of the time. Also, while I agree it is not the best metric, HCP + hearts >= 19 is certainly a reasonable one -- the actual opener in particular would have benefited from it. One of the reasons I like to post sims + criteria is to get input from the accomplished players on whether my criteria are worthwhile. If you don't like the criteria, instead of just saying "this criteria sucks", how about suggesting a better one, one that you use? It will only take a few minutes to evaluate.

Presumably the point of the first condition was to exclude 6222 and 7111 shapes? Good catch, I normally have a function for normal preempts that uses all three of those metrics, but this is white/red 3rd. Most people tend to be a little loose here, so I pulled it down a notch without thinking too much about the possibilities.

Looks like a hand for a sim. Giving West and North passed hands, East an aggressive w/r 3rd seat 3S open (at least 9 cards in longest two, good 6-card suit or mediocre 7-card suit): Sim results over 1000 hands: 4M makes but 3NT doesn't = 197 3NT makes but 4M doesn't = 152 Both make = 381 Both go down = 270 Average tricks in major = 9.651 Average tricks in NT = 8.502 Looks like 4H > 3NT > PASS. If you can stomach a few 500-800s (and why not, it's matchpoints), bid 4H. Also, 3NT may be slightly demoted in the sim over real life, because the sim thinks the opponents will always find a killing club lead when that's right.

I am not a fan of barometer pairs as currently implemented, because it feels it adds yet another luck component to the equation. Let us say you are tied for the lead going into the final round and you are up against a pair who knows they need a good board to get into the overalls, a bad/average board is irrelevant to them. Meanwhile, your competitors are going up against a pair that is having their usual 40% game, so they have no incentive to do anything weird. Now say your final-round opponents reach 4S and need to guess a queen knowing that one of you holds 3 cards in the suit and the other holds two. Your opponents will be highly motivated to take the anti-percentage play, while your competitors' opponents will not, and you may gain a top or bottom simply because of their current standing, a factor which you have no control over. Granted, you cannot guarantee people playing normal bridge on every board, but I don't see why the conditions of contest have to encourage even more deviations. From a game-balance perspective, I would have no objection to barometer scoring for KO TEAMS, if both tables play the boards in the same order and there was synchronization like "hand-for-hand" play in poker -- you can't go onto the next hand until the other table has finished the previous one and all sides know the current state of the match. But I suspect that would not be as fun to play with all the delays waiting for the "slow table" to catch up after every hand.

That's a good question, but in practice, I find I infrequently want to balance over 1m - 1M - 1NT when the opponents don't have a fit and I don't have a hand that was worth an action initially. I grant you it's certainly possible, but I don't think it's highly likely. Responder knows way too much about opener's hand for my comfort. If someone can suggest parameters for bidding over this, it's easy enough for me to discard these hands from the opponent filter as well.

Note that I didn't put any additional constraints on the North hand such as removing hands that would judge to pass 1NT, such as 9 HCP 5332s.

Generating 1 million hands 1) 0.1154% 2) 3.1474% ----------------------- Sample size: 1000 hands North has exactly 5 spades, at most 9 HCP, South has a hand that would open 1D and rebid 1NT (and would have raised on some 3-card spade suits, as described earlier), E/W can have any hand (including those that would bid in real life) South average spade length = 2.271 1 spade = 132 2 spades = 465 3 spades = 403 4x1 = 84 2S makes but 1NT doesn't = 188 1NT makes but 2S doesn't = 121 Both make = 326 Both go down = 365 Average tricks in spades = 7.498 Average tricks in NT = 6.288 ---------------------- Sample size: 1000 hands Same N/S parameters, but now E/W are operating under the pass_functions described earlier. Average spade length = 2.23 1 spades = 140 2 spades = 490 3 spades = 370 4x1 = 77 2S makes but 1NT doesn't = 176 1NT makes but 2S doesn't = 110 Both make = 383 Both go down = 331 Average tricks in spades = 7.672 Average tricks in NT = 6.433 ----------------------- Apologies for the smaller sample size, but double-dummy analysis takes longer to run, and we're getting similar numbers (13-14% spade singletons) as the larger sample sizes. Bottom line, 2S seems to be superior to 1NT at IMPs on a 5-bagger even if we rebid 1NT fairly freely with a singleton.

I actually did remove the opponent constraints out of curiosity : 1 spade = 12.91% (7.47% are 4x1s) 2 spades = 48.69% 3 spades = 38.4% So it's similar, but slightly less likely to be singleton. This is including hands where north has 4 spades, 6 spades, gf, weak, etc. I actually wasn't trying to answer the question of how often we should rebid 2S over a 1NT rebid in this auction, I was just trying to see how often South would have a singleton spade after a real-life auction of 1D 1S 1NT with no enemy bidding. 30:1 felt wrong given that I have also taken to rebidding 1NT with a singleton. I will be happy to remove game-invitational+ hands, and hands without exactly 5 spades from the mix and report the results.

You haven't seen some of the weak twos we open. :( Just kidding, I'm not that psycho. Point taken.

Where do you get this? This number could easily mean inviting is correct (and does mean that to me). Justin, you are correct. To rephrase: given a "false dilemma" of bidding 4H and passing 2H, bidding 4H rates to be the better choice. But this ignores the superior third choice, the invite. Obviously inviting is superior to bidding 4H for the reasons you mentioned. I just wanted to highlight to my disbelieving partner that if I held 6, just blasting game was better than passing. :( And yes, the rebid of 2H tends to be 5 cards even more than the rebid of 2S. So the concept of "2H guarantees 6" is flawed. But the result that game is percentage opposite 6 hearts was not immediately obvious to me or my partner. By the way, one nice thing about all this simulation work is that I am building up a library of functions which I can use to capture judgement heuristics and then reuse them for different hands in similar situations. As you can see this library is currently in a primitive state, and I find your comments invaluable to refining my functions.

Fred, I would consider on this auction that most non 5332s would be able to bid 2H or 2D (for you probably bidding 2D via a 2C relay). Like 5-4 majors bids 2H obv, 5-4 with diamonds gets out in 2D. So the only real non 5332s here hands with side clubs. Probably 5332s are more common than hands with side clubs (not sure?) so if you pass with most 5332s it seems like 80 % was an overbid. Anyways I feel like you and I are pretty close in what we do actually. We seem to be the same with 5332...I guess I pass a lot with 5314 also when you wouldn't, but with 5134 I would bid very often and 5224 would depend on my suit quality (I would need good spades), and I would always bid with 5-5. This is actually a good discussion for me because I just played a hand where my partner held AQxx 432 ATxx A2 Matchpoints, both vul Our auction went : 1D 1H 1NT [1S anti-system] 2H ? Partner passed, I thought he should have invited to 3H given the immense power of aces in a suit contract. Surprisingly, when I simmed the hand, if partner is guaranteed to hold 6 hearts (but never 6-4 shape) with 4-9 HCP, then game is 55%, indicating he should bid 4H! A big factor is that the opponents are passing -- meaning we get good breaks. After adding decent 5-card heart suits (QJTxx or better) to the mix, game is 46%, suggesting an invite is probably ok, even at matchpoints. Now that I can see some better judgement parameters for the rebid of 2H (never 5332 unless weak outside hearts, always otherwise), I'll be happy to rerun this.

Turns out it wasn't so hard to throw this parameter in. Results with no South round-suit singletons or worthless doubletons containing 3 spades to a high honor, 10000 hands dealt: 1 spade : 799 2 spades : 4925 3 spades : 4276 So, the odds appear to be 11.5 : 1 against. Can you add in 1444 and see how that changes it? Good point. That was rather careless of my parameter setting to filter out 1444 hands as well as [32]44 hands which ought to rebid 1NT. South now does not have : * 6 diamonds * 4 spades * 5 diamonds and 4 clubs (but could have 4 diamonds and 4 clubs) Note that South always bids 1D with 4-4 in the minors -- I don't make any judgement calls on whether to override 4-4 in the minors to 1C. I also added another stat, to track the average HCP of the singleton, and I increased the sample size to 100000 hands. New results: Average spade length = 2.22771 Average singleton spade HCP = 0.8676683039583936 0 spades = 0 1 spades = 13844 (4x1 = 8084) 2 spades = 49541 3 spades = 36615 Wow. That was quite a difference. So the majority of 1NT singleton rebids are 1444, and the odds against a singleton for the rebid are now 6.2:1 against.

Turns out it wasn't so hard to throw this parameter in. Results with no South round-suit singletons or worthless doubletons containing 3 spades to a high honor, 10000 hands dealt: 1 spade : 799 2 spades : 4925 3 spades : 4276 So, the odds appear to be 11.5 : 1 against.

Fred, I think I can provide a slightly better simulation. As you may have noticed, I've been playing with scripts that model all the hands, using Thomas Andrews's deal program. The process is not completely robust, but I think the results are still interesting. Parameters: * South has 12-14 HCP, a 1D opening, at most 5 diamonds, at most 3 clubs, at most 3 spades. [This is robust.] * West does not have an overcall, preempt, or takeout double of 1D. [Not as robust -- may contain hands like 85 T94 75 KQJ943, or hands that might bid Michaels or U2N -- still haven't added support for this yet.] * North has any hand that would respond 1S to 1D, in a Walsh style -- could contain a longer suit if North holds non-game-forcing value. [Robust -- i.e., does not contain hands that are 4-4 in the majors.] * East does not have an overcall, preempt, or takeout double of 1S. [same comment as applied to West's pass.] * No hands where South holds 3 spades are thrown out -- we assume South needs 4 spades to raise. [Robust.] ----------------- In 1000 deals that fit these parameters, South has: 1 spade 66 times 2 spades 426 times 3 spades 508 times So, with the slightly flawed opponent passing routines, the odds have doubled from 30:1 against to approximately 15:1 against. Eliminating some 3-card holdings would increase the odds even more. Perhaps any 3-card spade holding with a stiff, or any 3-card spade holding containing a high honor and a worthless doubleton on the side? I can program that in.

We = me and most of the partners I play with. The 4-level leads to some disagreement, though. Another related auction that came up: 1D (2NT) Dbl (4C) ? Double = values, defensively oriented Is Pass forcing here, especially after advancer appears to like one of intruder's suits?

I've been busy codifying Forcing Pass agreements, and I would like the opinions of the group on whether responder's cue-bid promising limit-raise values or better sets up a force at the 4-level. We certainly agree it sets up a force at the 5-level, and our philosophy is that vulnerability is irrelevant. However, what about : 1H (1S) 2S (4S) ? Is pass forcing? 1S (2H) 3H (4H) ? Is pass forcing?

Sadly, I'd have to agree with mrdct on one thing -- all top-class players do not necessarily exhibit professional behavior. Joe Grue in particular has reminded me of a spastic puppet at times, and yet I would be the last to question his ability. Perhaps "moronic" (stupid, doltish) is not quite the right adjective to describe irregular behavior, although I am sure Fred feels that way. How about "inappropriate" or "unprofessional"?

Good questions. I had to rerun the sim because I forgot to specify that RHO did not have a hand that could act over 2H. This is true for the majority of hands, but there are a few hands which greatly distorted the results against NT. The results have therefore changed. New results: Average tricks in suit = 8.652 Deviation = 1.2435603895438436 0-6 tricks in suit = 32 Makes 1 of suit = 145 Makes 2 of suit = 283 Makes 3 of suit = 287 Makes 4 of suit = 253 Average tricks in notrump = 7.409 Deviation = 1.6668825685984885 0-6 tricks in notrump = 289 Makes 1NT = 234 Makes 2NT = 216 Makes game in NT = 261 Notrump is still 1.2 tricks worse because when it goes down, it goes down big. Game chances appear similar in both strains, though. The simulation parameters: LHO has 5+ spades, at most 21 HCP, will not have 5[332] with 15-17 HCP, 2+ quick tricks, and a hand that satisfies to the rule of 20 (two longest suits + HCP = 20). Partner has 5+ hearts, 1+ quick trick, at least one heart honor (ten or higher), does not have a side 5-card minor, and has a hand that satisfies to the rule of 20. RHO has at most 9 HCP, does not have a hand that satisfies the rule of 18, and does not have a spade raise (could have 4 spades without a singleton with <6 support points). As Justin mentioned, it is more possible to end up in hearts after 2NT than notrump after 3H. I do not have an algorithm to determine rebids, that becomes very complicated and uses more judgement. I could throw out hands where partner has a spade void and 6 hearts, for example, but such hands tend to be uncommon. RHO's average spade length on this auction is below 3, so partner tends to hold a spade and will be less inclined to pull to hearts. I do not know how to do the double-dummy analysis forcing a spade lead, but given that LHO has most of the high cards and 5+ spades while RHO is frequently balanced and/or weak, a spade lead is often the best defensive start. Sometimes, LHO has a side suit in clubs which is a better start (and which a human player would also find), so I am reluctant to force a spade.

Now that I'm home, I decided to see just how different these two hands are. I ran a sim on the trick-taking potential of AJx QJTxx AJx xx with hearts trump after a standard 1S opening: 7.77 tricks on average 7 tricks 20% 8 tricks 22% 9 tricks 15% 10+ tricks 18% 0-6 tricks [potential for disaster] 25% And to repeat my results on K4 JT874 J92 AQ5 : 7.0 tricks on average 7 tricks 16% 8 tricks 17% 9 tricks 16% 10+ tricks 9% 0-6 tricks 42% Finally, a third hand that I imagine would feel better for some players -- xxx AKJxx Axx xx : 7.5 tricks on average 7 tricks 22% 8 tricks 23% 9 tricks 14% 10+ tricks 12% 0-6 tricks 28.5% The QJTxx hand with two side aces plays better than the AKJxx hand with a side ace. Also factor in that the second hand has just one keycard, making an enemy double much more likely. To me hands 1 and 2 are simply not comparable.

I've made better overcalls but 2♥ on AJx QJTxx AJx xx is hardly comparable to felinicide. It seems clear to me, even opposite a passed hand. Have you forgotten that we are favorable? The opponents are unlikely to go headhunting at these colors with at most 2 trump honors and 2 aces. And if you don't overcall, good luck pushing them up or finding a nice distributional game (x Kxxx KTxxx xxx, QTx Kxxx x xxxxx). It even has lead-directing and obstructive value. It's not perfect, but I would much rather bid 2♥ than pass here.