Mixed Strategies at matchpoints

[jdonn]

Say I'm playing these two boards against the pair whom I believe to be the best pair in the room. Therefore, my score on these boards is likely to be worse than the score that all of the other North/South pairs, since the best pair are more likely to produce a successful action. If I make the "normal" raise to 4H on the first, is it not likely to be an auction duplicated at every other table in the room? Therefore, I am potentially disadvantaging myself if I produce the normal action, and so a mixed strategy/tactical bid/psyche is more likely to be successful.

What you describe is the type of hand where you SHOULDN'T be swinging, because you are fortunate enough to have a completely normal action in the bidding that is likely to be produced at other tables. Essentially you know this hand is more likely than normal to be flat, which is exactly what you want against better pairs.

[awm]

Adam do you mean Scott and his dad? If so, have you considered other reasons they might score that way? I can think of one...

Obviously there are many reasons pairs may score this way, and I'd rather not speculate on it except to say that it seems likely such pairs "change tactics" (either intentionally or for psychological reasons) when it seems like their session is going well or poorly. Certainly their board results are not likely to be independent random trials.

 

My point is just that there are high-variance pairs, who frequently have sessions which are either much better or much worse than whatever their expected score is. In fact I can think of many such pairs!

[OleBerg]

Suppose every pair in the room discovers this secret of success against strong pairs. The strong pair now is constantly facing opponents who bid singletons, randomly bid 3NT instead of looking for 6M, and generally deliberately take anti-percentage actions on every board (in addition to all their usual errors).

 

I would expect the strong pair's scores to improve dramatically (which admittedly is just another way of saying that I think this is a terrible strategy). If your theory is correct though, the strong pair would get worse scores than they used to.

Not necessarily.

 

They would score more matchpoints on the average, but they might lose a few places sometimes.

 

Imagine this extreme example:

 

A pair is so much stronger than all the other pairs in the tournament, that they will normally always win. If everybody used the strategy, once in a very seldom while, they would get unlucky, and the most lucky of the other pairs would win.

[OleBerg]

 

Say I'm playing these two boards against the pair whom I believe to be the best pair in the room. Therefore, my score on these boards is likely to be worse than the score that all of the other North/South pairs, since the best pair are more likely to produce a successful action. If I make the "normal" raise to 4H on the first, is it not likely to be an auction duplicated at every other table in the room? Therefore, I am potentially disadvantaging myself if I produce the normal action, and so a mixed strategy/tactical bid/psyche is more likely to be successful.

 

Not really.

 

Lets say your expected score against this pair is 45%. Now when you make an offbeat action, the pair will highly likely be able to handle it. So you simply reduce your expected score to, say, 35%.

 

What you do is to make it more likely that the board is a swing board. So it increases the likelyhood that you will get a top this way, but it increases the risk of a bottom even more. So you swing the board, but your downside gets bigger.

[OleBerg]

There's been a lot of talk about swinging. In my opinion, there is one good way to do this, if you play in a field, where you feel you are at a disadvantage:

 

Play something different. Not silly or dramatic or wild, just different.

 

If the standard is 2♦ = weak, play multi. If it is multi, play weak.

If people play 15-17 NT's, play 12-14 NT's.

If they play Stayman and Jacoby, play Two-way Stayman.

If they play standard signals, play reverse.

 

And so on.

 

If you assume the methods have equal merit, you increase the variance without costing yourself equity. The best way to try and win, when you are outgunned.

 

 

A side benefit, which really has nothing to do with the conventions as such, is that people will generally be less well prepared against uncommon methods.

 

 

Edit: And finally regarding MP's: The "Who makes which mistakes when, and against whom" - factor, already makes almost all tournaments random enough to give you a chance, if you simply aim to make as few mistakes as possible. On some days you will be the lucky one, against whom they all make their mistakes, and there is no reason to reduce your expected score against "the best pair in the room."

[Mbodell]

The style opponents have adopted is not particularly sound and may hand out more good boards than bad. But a lot of the good pair's natural advantages have been nullified. I wouldn't be surprised to see their expected score go from 65% to 60% or something like this. Of course, if people behaved the same way against an average pair, the average pair may well have their score go up from 50% to 55% because of the unsound competitive actions too.

I'm not sure if this is what you mean, but what I'd expect is that the pair might go from a roughly normal distribution with mean at 65% and a std dev of 5% to a mean of 70% and a std dev of 15%. That is their expected matchpoints would go up, but so would the distribution. If you were a pair that was going to play the same direction and you always score, say, 58% you'll win more often (but when you lose you'll lose by more on average) against the pair facing the swinging.

 

It certainly is true in the abstract. It also is true in some situations like poker tournaments (when outclassed go all in more to have fewer decisions with larger variance in outcome rather than more "normal" actions).

 

In practice it is possible that no one who is good enough at creating swings and/or estimating swings is also out classed and/or not going to do better playing down the middle.

[Jlall]

The amazing thing about these threads is people act like they know that some abnormal action is very slightly -EV so they should go for the higher variance. If you get some situation where this is possible it might be right to go for it, but doing things like bidding 1S are horribly -EV imo. It's just very bad and people are acting like its pretty close. Maybe if you aren't that great you aren't good enough to judge what is the best action, what is the next best action, how close in EV they are, what the field rates to do, etc etc.

 

Also if it's a pair game you can start out by not swinging and then at the end do it if you need to. Maybe you start out doing normal stuff, get some gifts, and have a good game. If you start having a bad game you can change strategies. You don't have to adopt an all or nothing strategy on high variance -EV stuff. I think swinging on board 1 is always going to be bad.

 

Also, I hate to say it but bidding is not that important in winning at MP. MP is all about making all your tricks etc. Your biggest edges are always going to be in the play, not some random bidding scenarios. A lot of swing positions come up late in the play where you have a ton of info and can back your judgement and be huge +EV. If you just do random stuff before that you lose that possibility.

 

Bidding is so overrated in MP it's amazing to me. I know this might be a controversial view, but I really believe it to be true. Get to normal contracts and create some edge in the play. Learn how to do that and you'll win a lot in MP.

 

-Jlall, never won a national MP pairs.

[Jlall]

For instance on the last hand, transferring and splintering easily allows you the chance to use better judgement than the field, even if it's normal. It's a great chance to win the board with +EV bidding with lots of info by getting to a good slam or avoiding a bad slam. You might even get to 6N. You might even get to 3N if you transfer and splinter and partner bids 3N and you pass. You might get to a normal contract and win a swing with good card play when you have lots more info to work with. Etc etc. Just hoping to get lucky by blasting 3N or blasting slam is just not that good. Even if your opps are awesome, this is your hand and they're passing so who cares, it's your board to win or lose. Save the swing bids/plays to later when you have an edge.

[Jlall]

Adam do you mean Scott and his dad? If so, have you considered other reasons they might score that way? I can think of one...

Obviously there are many reasons pairs may score this way, and I'd rather not speculate on it except to say that it seems likely such pairs "change tactics" (either intentionally or for psychological reasons) when it seems like their session is going well or poorly. Certainly their board results are not likely to be independent random trials.

 

My point is just that there are high-variance pairs, who frequently have sessions which are either much better or much worse than whatever their expected score is. In fact I can think of many such pairs!

Isn't entirely likely that they correctly start swinging when they are having a bad game early on? Maybe they play normal when they are getting 60+, or they started bad and swang and made it back, but when they get 40 it's them starting bad with normal things and then swinging and it doesn't work. This is completely normal in pairs imo.

 

I don't understand why it's expected that they start playing some -EV high variance style to begin with to achieve this.

[cherdanno]

For instance on the last hand, transferring and splintering easily allows you the chance to use better judgement than the field, even if it's normal. It's a great chance to win the board with +EV bidding with lots of info by getting to a good slam or avoiding a bad slam. You might even get to 6N. You might even get to 3N if you transfer and splinter and partner bids 3N and you pass. You might get to a normal contract and win a swing with good card play when you have lots more info to work with. Etc etc. Just hoping to get lucky by blasting 3N or blasting slam is just not that good. Even if your opps are awesome, this is your hand and they're passing so who cares, it's your board to win or lose. Save the swing bids/plays to later when you have an edge.

Yeah, we should be happy we have the judgment decision on this one, why throw away that advantage? Same as throwing away the advantage from the UI on the first one.

[MFA]

This is an interesting thread.

 

My view on 'swinging' in general is pretty harsh. I see it as a sign of lack of competitive toughness. That one is willing to give up on best strategy for the hope that something fortunate will happen after some random bash.

 

Especially so, if one is swinging against good players only. It is a big "celebrity bonus" for the well-known players when underdogs are willing to back longshots instead of playing bridge. I would always prefer my underdog opponent to play like that. If they are playing with bad judgement in general, there is no reason why their bashing should be well-judged in particular. So they are just giving up even more equity.

 

In general players underestimate the natural variance in bridge - it is there already with normal play - and grossly overestimate the closeness between the normal action and the 'swing action'. So often the swing action is just so heavily against odds.