bypassing spades in NT rebids

[helene_t]

I am a bit perplexed by all this talk about playing with the field. You don't know what the field does. Even if everyone plays the same general approach there will usually be judgement and style differences. You might carefully navigate to the inferior field contract, hoping to make a top by superior play, only to discover that you are the only declarer to receive the killing lead, or that an unlikely split makes your superior line lose. Or that half of the people who declared this board were better declarers than you. Or that most of them found the superior contract. Or that your solid play gives you 60% while you needed 90% to get in the prices.

 

Stephanie gave a good example of a situation where you want to play low variance, namely a qualifying round. But generally it is not clear if variance is good or.bad.

[awm]

I've played both styles pretty significantly (bypassing in my current partnership with Howard Liu, bidding up the line with Elianna and Sam). The reality is that this will usually not make much difference. If you play decent check-back methods, it should not matter on invitational or better hands. You have plenty of space to sort out your major fits and opener's potential unbalanced shape.

 

There are two main places where I've found this to matter, both most often on partial hands. Bidding up the line gets you to better part-score contracts, because you don't miss 4-4 spade fits, and because you can sometimes play 1♠ in a moysian fit. I have not found it to be the case that we often play 2m on a 5-3 after opener shows an unbalanced hand, or that 2m would often be better than 1NT in these cases. Of course, this is all much more significant at MP scoring!

 

The second place is that opponents seem to make worse leads against 1NT when we bypass spades. Some of this is a lack of awareness of the style, which feels a little like bad disclosure (and in fact some opponents have complained that we should alert, but it's not alertable by any official rules I'm aware of). However, I do think that opponents truly have less information here. Of course, this advantage is much less if we land in 3NT because of check-back or lack thereof (often they have a lot more information about responder's hand on these auctions, which compensates for less about opener).

 

I will comment that things are different in a weak notrump system, where it seems that bypassing spades to rebid 1NT carries a lot more information about strength (strong notrump) that might make it easier to bid to the right games.

[mikeh]

I've played both styles pretty significantly (bypassing in my current partnership with Howard Liu, bidding up the line with Elianna and Sam). The reality is that this will usually not make much difference. If you play decent check-back methods, it should not matter on invitational or better hands. You have plenty of space to sort out your major fits and opener's potential unbalanced shape.

 

There are two main places where I've found this to matter, both most often on partial hands. Bidding up the line gets you to better part-score contracts, because you don't miss 4-4 spade fits, and because you can sometimes play 1♠ in a moysian fit. I have not found it to be the case that we often play 2m on a 5-3 after opener shows an unbalanced hand, or that 2m would often be better than 1NT in these cases. Of course, this is all much more significant at MP scoring!

 

The second place is that opponents seem to make worse leads against 1NT when we bypass spades. Some of this is a lack of awareness of the style, which feels a little like bad disclosure (and in fact some opponents have complained that we should alert, but it's not alertable by any official rules I'm aware of). However, I do think that opponents truly have less information here. Of course, this advantage is much less if we land in 3NT because of check-back or lack thereof (often they have a lot more information about responder's hand on these auctions, which compensates for less about opener).

 

I will comment that things are different in a weak notrump system, where it seems that bypassing spades to rebid 1NT carries a lot more information about strength (strong notrump) that might make it easier to bid to the right games.

 

 

My experience has been different from your, tho maybe because I rarely play anything but imps. There, avoiding the rebid dilemma after 1♣1♥1♠ on Qxx AQxx 10xx Jxx is fairly worthwhile: I can safely bid 2♣.

 

As for the lead, my practice has always been to announce that the 1N doesn't deny spades, unless I am playing serious bridge, in which case it is for the opps to ask, and they either already play that same style or at least are aware of the possibility. Not announcing against the typical lol (of either gender) in a swiss or early stage of a regional feels wrong to me, even if technically ok.

 

In addition, concealing declarer's hand is always more useful than concealing responder's. For one thing, opening lead is through dummy and into declarer, and that is an important difference. In addition, dummy is revealed early, while declarer's hand often can't be reconstructed for at least several tricks.

[aguahombre]

For the bypassers, when responder has inv+ values it seems neither 2-way checkback nor plain PLOB adequately compensates. 2S is needed to show the suit, and that removes it as an effective tool in sorting out both Opener's size (within the NT rebid range) and shape..at a convenient level. The importance of this wrinkle --compared against the plusses mentioned by Mikeh is questionable. Also, the importance of being able to bail out in 2 of Opener's minor is questionable. But, they are factors in our choice.

[Jinksy]

Is XYZ particularly prevalent in the US? It never would have occurred to me to mention it to UK opps, on the grounds that I've never encountered any pair who claim to play it.

 

I guess that might be related to weak NT being prevalent over here.

[mikeh]

For the bypassers, when responder has inv+ values it seems neither 2-way checkback nor plain PLOB adequately compensates. 2S is needed to show the suit, and that removes it as an effective tool in sorting out both Opener's size (within the NT rebid range) and shape..at a convenient level. The importance of this wrinkle --compared against the plusses mentioned by Mikeh is questionable. Also, the importance of being able to bail out in 2 of Opener's minor is questionable. But, they are factors in our choice.

I don't understand your concern about sorting out values. I suppose it depends on the scheme. Here's what I play:

 

2♣ puppets to 2♦, to play or about to make an invitational action. If responder bids 2♠ now, it shows 5+ hearts and 4+ spades, longer hearts always

 

2♦: artificial gf, opener to make cheapest descriptive action

 

2♥: if playing weak jumpshifts, then this is constructive but less than invitational. Opener will rarely move but is allowed to do so on exceptional hands. The constructive info is primarily to assist in bidding and defence if the opps balance. If not playing weak jumpshifts, then this is simply 'to play'.

 

2♠: invitational, precisely 4=4 majors

 

2N: puppet to 3♣, usually to play but can be various slam tries with 4 hearts and 5+ opener's minor, with all values in the two suits

 

3suit: slam try. If new suit, including opener's minor, then 5-5 or better, concentrated values, no side control. If 3♥, then rejects 3N as playable contract (allows 3N to be used for other purposes). With COG long heart suit, go through 2♦

 

3♠: autosplinter (exception to metarule that 3new suit is natural)

 

I don't recall ever having much trouble sorting things out with this style.

[aguahombre]

Is XYZ particularly prevalent in the US? It never would have occurred to me to mention it to UK opps, on the grounds that I've never encountered any pair who claim to play it.

 

I guess that might be related to weak NT being prevalent over here.

If we can gather from the North American BBO contributors..yes some form of XYZ seems to be used by many thoughtful partnerships --- and abused by a whole lot more.

[mycroft]

Then design a system that gives you 65% :rolleyes:

Rolleyes is right. As a system wonk, in the end, bridge is a game of card play, and I admit that system can't get you 65% (at least not without sufficient card play to make the better contracts, at which point...)

If you start with a system that gets you to higher percentage contracts, superior card play will only increase your advantage. If you voluntarily throw away your advantage by playing the same system as hoi polloi, you are decreasing the gap between you and the average/below average players.

Not necessarily. Look at it this way:

 

If I play the field contract, the field-way up, my expectation is 60ish% (it's not, of course, but pretend I can play).

If I play the field contract, the wrong way up, some large percentage of the time it doesn't matter. When it does matter, it's random whether I'm behind or ahead. When I'm behind, I expect to lose 60ish% with my zero, or 40ish if my superior play gets me back to average. When I'm ahead, I expect to win <40% with my top. So my randoms are a net loss that the system has to gain back for me (and when we're talking weak NT v strong NT, that's a *lot* of randoms - most openers with 11-17 sort of balanced will end up played the other way up or with much different information available to opps)

If my system gets me to a superior contract, again, it either works or it doesn't. If it works, my card play doesn't matter, but again I'm gaining <40% (say I find the slam. If it requires superior card play to make, how many more MPs am I getting for it than for 4+2?) But if it doesn't work, my card play again doesn't matter, but I'm losing 60ish%! So the system wins have to actually pay off more than 60% of the time - not just "higher percentage contracts" - just to break even. Now add the extras you need to recover from the random system losses (and no matter how superior your system is, there will be random system losses), above, and you might need to build a 70% system to not lose against playing down the middle and letting card play get you to your expected 60%.

 

It's the tradeoff of a high-variance system, whether that variance is built into the system, or whether it's just different - even if you stack the deck in your favour, when you put your results in the hands of the Card Gods, sometimes the draws end up against you. And when they do, your card play "advantage" goes away - at best, it limits the losses.

[johnu]

Rolleyes is right. As a system wonk, in the end, bridge is a game of card play, and I admit that system can't get you 65% (at least not without sufficient card play to make the better contracts, at which point...)

 

Not necessarily. Look at it this way:

 

If I play the field contract, the field-way up, my expectation is 60ish% (it's not, of course, but pretend I can play).

If I play the field contract, the wrong way up, some large percentage of the time it doesn't matter. When it does matter, it's random whether I'm behind or ahead. When I'm behind, I expect to lose 60ish% with my zero, or 40ish if my superior play gets me back to average. When I'm ahead, I expect to win <40% with my top. So my randoms are a net loss that the system has to gain back for me (and when we're talking weak NT v strong NT, that's a *lot* of randoms - most openers with 11-17 sort of balanced will end up played the other way up or with much different information available to opps)

If my system gets me to a superior contract, again, it either works or it doesn't. If it works, my card play doesn't matter, but again I'm gaining <40% (say I find the slam. If it requires superior card play to make, how many more MPs am I getting for it than for 4+2?) But if it doesn't work, my card play again doesn't matter, but I'm losing 60ish%! So the system wins have to actually pay off more than 60% of the time - not just "higher percentage contracts" - just to break even. Now add the extras you need to recover from the random system losses (and no matter how superior your system is, there will be random system losses), above, and you might need to build a 70% system to not lose against playing down the middle and letting card play get you to your expected 60%.

 

It's the tradeoff of a high-variance system, whether that variance is built into the system, or whether it's just different - even if you stack the deck in your favour, when you put your results in the hands of the Card Gods, sometimes the draws end up against you. And when they do, your card play "advantage" goes away - at best, it limits the losses.

 

??? Having a better bidding system also includes playing the contract from the most advantageous side, not giving the defense a blueprint for defending when it matters, etc. It makes zero sense to say that you got to a 60% contract but only average 50% or less in real life. I call that a 50% expectation, not a 60% expectation. Don't be distracted by variance. Sure, for any given hand a terrible contract can turn out great and a great contract can end up with a zero, but over 100 or 1000 hands, higher expectation systems will come out ahead. If you don't come out ahead in the long run, either you are very unlucky or the valuation of your system was incorrect.

 

That's not to say you can't win in the short run with a high variance, below average expectation. Everyone has seen a team of bad players beat a team of world class players in a short swiss match or even a short knockout match, or a pair of bad players give a couple of zeros to a pair of world beaters in match points.

[akwoo]

Let's try a slightly different example, johnu:

 

For simplification, let's suppose that, when you get to a better contract than the field, you get 100%, and when you get to a worse contract, you get 0%. (If you don't like these numbers, put in 90% and 20% for a good player and 85%/15% for an average one. We can tweak everything else sufficiently to make it work.)

 

Let's say that you are playing a system where

 

25% of the time you get to a better contract than the field

60% of the time you get to the same contract

15% of the time you get to a worse contract

 

That's a pretty good system, right?

 

Well, if you're playing just as well as the field, it's a good system - you score .25+.30 = 55% on average (or 53.5% for 85/50/15).

 

Let's suppose, however, that you play much better than the field, and when you end up at the same contract, you get 70%.

 

Then your result playing this system is .25+.42 = 67%. (At 90/70/20, it becomes .225 + .42 + .03 = 67.5%)

 

Playing this system instead of the field system has now reduced your expected score from 70% to 67%!

[mycroft]

What I'm trying to explain is that because your expectation is > 50% already, your system has to do better than better than that to beat "play down the middle". You can, in fact, lose in the long run with a high variance, above average expectation system - if you're sufficiently above average expectation already.

 

It's a standard matchpoint decision:

- What is the chance that X is right over where you are now, and

- What is the expected win if you're right, vs the expected loss if you're wrong.

 

Throw away all the "doesn't matters" hands.

Here, the expected win from getting to the right contract, played the right way, giving the opponents different information that helps rather than hinders you, is <50% (not quite 100% - 50+%). The expected loss from getting to the right contract (that happens to be wrong this time), or played the right way (which happens to be wrong this time), or in the process giving the opponents information that helps them - is >50% (not quite 0% - 50+%). Sure, you get more smaller wins than your larger losses (or you wouldn't be in the right spot), but is it enough to get to what you'd get by playing down the middle? Note that in addition to those, there will be hands where you're forced into the wrong contract by system (because more often than not your system gets you to the righter contract, but this is one of the other hands), which will also win sometimes (< 50% of the time, for + <50% of the MPs) and lose sometimes (> 50% of the time, for - >50% of the MPs). Your card play advantage will eat into the losses and add to the gains, as will others that field-protect for you, but not enough to even balance that, never mind get it to 60-when-you're-right, 40-when-you're-wrong.

 

For me, the 50% cardplayer (shhh), it's a totally different question. If my system is 60% on the field, then I get 60% over the year. It'll be a bit pajama, and the variance will be high, but it will be well to my advantage. In addition, because I'm presenting the good card players with problems that a) the rest aren't getting, and b) they're not as familiar with as either I am, or as they are with "normal", they're likely not going to be as good card players as the usually are. That's not worth much (certainly not as much as the "they only play this to confuse us with their unfamiliar systems" people believe), but it is worth something.

 

Or as I said to the highest masterpoint holder in our unit, when he asked "but [EHAA] totally randomizes the results. Why would you want to do that?": "Say I flip a coin twice for all the matchpoints on these two boards; my expectation is 50%. Tell me that's less than what I would expect against you playing straight."

 

Question, just for the amusement:

You know that 6♣ is mildly odds-on (say, it's "9 without the Q" and some chances, so 55, 56%). You also know that the field, because of their system, is never going to even sniff at it - they'll all be in 3NT, which should be close to 100%. Do you bid it?

 

Now I tell you that you are a seeded pair in a field of 75 tables in a city where the sectionals draw 45, including a few from out of town. Still bidding it? Or are you going to bid 3NT with the rest of the room, knowing you'll take all the tricks and be solidly A+?

 

Does it make a difference if I tell you that while top on most boards is 50, this board is only going to be played at 16 tables, and your score is going to be factored from a 15 top to 50?

 

Does it make a difference if I tell you that the auction's at 3♥ now, and you could still be off two fast tricks in a suit (but the slam's about 75% if you're not), and if you try to find out, you'll lose the chance to play 3NT (and will sit in 5♣ for a clear, if potentially shared, bottom)?

 

These are the boards that are wins for your "better system"! And I know this all too well, having played Precision with 14-16 NTs and lots-a-gadgets for many years. These were the boards that greyed my hair - "I know this contract is better, but is it better enough to take the zero if this time it's wrong?"

 

[Edit: Aaaaand, while I'm typing, akwoo says what I am saying in a third the verbiage with double the comprehension.]

[Cthulhu D]

Isn't this basically a justification for serious events to be scored Cross Imps? This analysis only applies at matchpoints, due to the weird equating of 'bidding a slam' to 'getting 1 extra overtrick'. I think basically every serious event around here is scored X-imps (or butlered imps or similar), so obviously I've never really considered the field system, it only matters on random club nights.

[aguahombre]

Isn't this basically a justification for serious events to be scored Cross Imps? This analysis only applies at matchpoints, due to the weird equating of 'bidding a slam' to 'getting 1 extra overtrick'. I think basically every serious event around here is scored X-imps (or butlered imps or similar), so obviously I've never really considered the field system, it only matters on random club nights.

Yes, the weird idea of an event where your placement depends on scoring better than other pairs, regardless of numerically how much better --- with every board being equal to every other board regardless of whether it is a part-score battle or a slam hand --- has been around for much too long. Good thing they aren't considered to be serious events.

[Cthulhu D]

Yes, the weird idea of an event where your placement depends on scoring better than other pairs, regardless of numerically how much better --- with every board being equal to every other board regardless of whether it is a part-score battle or a slam hand --- has been around for much too long. Good thing they aren't considered to be serious events.

 

Mhmm, sarcasm. I know it's popular in America, but it *is* a very weird feature of the scoring system that you are encouraged to play methods that you think are worse, because that results in a better expected score.

[helene_t]

(Must resist the temptation to rant about IMPs vs MPs - would be too much of a threaddrift)

 

Anyway, either method is obviously inferior to T-Walsh.

[aguahombre]

I don't believe anyone plays methods they consider to be worse for the conditions of the event they enter. Anyway, I am sure Kerri and Jack would have more significant input on the subject than I. They both have a bit of experience at different types of Bridge contests.

[Vampyr]

Isn't this basically a justification for serious events to be scored Cross Imps? This analysis only applies at matchpoints, due to the weird equating of 'bidding a slam' to 'getting 1 extra overtrick'. I think basically every serious event around here is scored X-imps (or butlered imps or similar), so obviously I've never really considered the field system, it only matters on random club nights.

 

IMP pairs is considered by many to be an inferior form of bridge scoring. As a world-class player once commented "it's like playing in a teams event where your teammates are the worst pair in the room".

[whereagles]

That's a bit of a silly statement. Sorry!!!

[mgoetze]

IMP pairs is considered by many to be an inferior form of bridge scoring. As a world-class player once commented "it's like playing in a teams event where your teammates are the worst pair in the room".

Yes, the main problem with Butler or Cross-IMPs is that it comes down to which direction you are sitting against whom on a couple of swing boards, with the rest of the boards being just filler so that you don't know exactly which boards are going to be the swing boards. If your opps manage to bid that hard-to-find slam, you're screwed. If you manage to bid that hard-to-find slam which goes down because of the 5-0 trump break, you're screwed. If your opps manage to find that unlikely "sacrifice" that turns out to be a double game swing, you're screwed. And so on.

[Vampyr]

Yes, the main problem with Butler or Cross-IMPs is that it comes down to which direction you are sitting against whom on a couple of swing boards, with the rest of the boards being just filler so that you don't know exactly which boards are going to be the swing boards. If your opps manage to bid that hard-to-find slam, you're screwed. If you manage to bid that hard-to-find slam which goes down because of the 5-0 trump break, you're screwed. If your opps manage to find that unlikely "sacrifice" that turns out to be a double game swing, you're screwed. And so on.

 

Quite so. Your "teammates" are not protecting you at the other table (which is why they are the worst pair in the room).

 

Here an arrow-switch is thrown in as a further randomiser, at least by some clubs.

 

There's nothing inherently wrong with a crap-shoot; in fact it can be a lot of fun. But I wouldn't want to have one in a serious event.

[whereagles]

That's funny, I've seen compelling arguments PRO x-imps.

[mycroft]

I don't think I've ever seen any arguments in favour of x-imps that weren't "in favour of x-imps over other IMP pairs scoring methods like Butler against datum".

 

There's a reason lots of people complain about (the result of a) 2-day Swiss qualifier into full-day KOs for a 7-day event and nobody complains about two days into the Reisinger final. There's a reason the Spingold is 6-7 days, and the Platinum Pairs/BRs/... is 3. Matchpoints may not be bridge - it's a great game, though - but it is a more skill/less luck game than IMPs (which is why there are "no" BAM events outside of Nationals; and why while BAM KO would be fun, it'll never happen (and why the "morning seeded KO" has died as well, combined with "if you expect to survive the first two days, you'd better be there all week")).

[Cthulhu D]

I don't think I've ever seen any arguments in favour of x-imps that weren't "in favour of x-imps over other IMP pairs scoring methods like Butler against datum".

 

Yeah, x-imps is clearly better than Butler

 

There's a reason lots of people complain about (the result of a) 2-day Swiss qualifier into full-day KOs for a 7-day event and nobody complains about two days into the Reisinger final. There's a reason the Spingold is 6-7 days, and the Platinum Pairs/BRs/... is 3. Matchpoints may not be bridge - it's a great game, though - but it is a more skill/less luck game than IMPs (which is why there are "no" BAM events outside of Nationals; and why while BAM KO would be fun, it'll never happen (and why the "morning seeded KO" has died as well, combined with "if you expect to survive the first two days, you'd better be there all week").

 

This is reasonable. I'm not sure "more skill/less luck game than IMPs" this is true, I think your argument is more accurately presented that it's a lower variance game, unless you can exactly equate the skills required.

 

But anyway, it's probably likely there is a solution that combines the two! I've played an event that was a hybrid of BAM and IMPs scoring before that I quite liked, you could logically do the same thing with matchpoints in a Swiss event. Score it something like this:

 

(VP Score of match at IMPs)+((Highest VP Scoring at imps in the field+lowest VP score at imps in the field)*(Matchpoint %))/2

 

I'm not sure that is correct, there are lots of ways to put the matchpoint score on the VP scale there and that is by no means the best one, but you get the idea

 

I think that would remove the weird incentives in both forms of scoring.

[johnu]

Let's try a slightly different example, johnu:

 

For simplification, let's suppose that, when you get to a better contract than the field, you get 100%, and when you get to a worse contract, you get 0%. (If you don't like these numbers, put in 90% and 20% for a good player and 85%/15% for an average one. We can tweak everything else sufficiently to make it work.)

 

Let's say that you are playing a system where

 

25% of the time you get to a better contract than the field

60% of the time you get to the same contract

15% of the time you get to a worse contract

 

That's a pretty good system, right?

 

Well, if you're playing just as well as the field, it's a good system - you score .25+.30 = 55% on average (or 53.5% for 85/50/15).

 

Let's suppose, however, that you play much better than the field, and when you end up at the same contract, you get 70%.

 

Then your result playing this system is .25+.42 = 67%. (At 90/70/20, it becomes .225 + .42 + .03 = 67.5%)

 

Playing this system instead of the field system has now reduced your expected score from 70% to 67%!

 

Cherry picking examples is a nullo way to analyze average results. I once heard of a non-math student complaining that you couldn't average a list of numbers because they were all different. :P You are saying that a 67% solution isn't as good as a 70% solution. Congratulations, you must have gotten a passing math grade :rolleyes:

 

Even though you are playing a better system overall, you may have worse results on any given hand. All that matters in the long run is your average results. Nobody is saying you will get better results on every single hand. If in the long run, you averaged 67% compared to the 70% you could have attained using the "field" system, why would anybody believe that the 67% system is better? A reasonable conclusion is that your "improved" system is actually worse than the field system, not better.

[Vampyr]

 

I think that would remove the weird incentives in both forms of scoring.

 

Hybrid scoring is great for teams, anyway. For pairs, again, might be fun but not for a serious event.