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Takeout v penalty some thoughts on stats

#1 User is offline   1eyedjack 

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Posted 2004-May-21, 18:53

I have been thinking about the expected gain or loss of doubling the opponents into game, particularly in an IMP game.

Received wisdom is that you generally need a defensive trick or two to spare when doubling into game. OK, some players make more risky bids expecting reticence in doubling, which affects the odds a bit regarding the justification of a double ... something of a "chicken and egg" situation, that ultimately converges on the minimum requirements for a "safe" bid and minimum requirements of a "safe" corresponding penalty double of that bid. However you define the safety cut-off there will be hands that are marginal.

2 situations to consider:

1) you are playing penalty doubles and are considering a marginal double of a partscore which, if it makes, would concede game.

2) you are playing takeout doubles and are considering a marginal pass of partner's takeout double which, if it makes, would concede game.

Going for the penalty in situation 2 appears to be less risky than in situation 1. The score conceded if it makes is the same, but the score conceded if you take an alternative decision differs. In situation 1 if you pass then the range of scores is narrowly limited to between a small plus and a small minus. Comparison with a contract doubled-into-game and made is a substantial IMP loss. In situation 2 if you pull it then you are inviting the opponents to double you, which could result in a penalty that is comparable with, or may even exceed, the score that would be conceded by letting them play in a cold doubled-into-game contract.

I was wondering what affect this might have on the overall frequency of doubling them into game. To simplify the problem I assume that the distribution of high card values between the hands is irrelevant.

A factor that increases the relative frequency of the penalty double in situation 1 is that partner's distribution need not be ideal for a takeout double in order to pass. If you map all of doubler's partner's distributions into situation 2, on many hands that you might consider passing a double you may not be presented with that choice because partner lacks the right shape to double. Does this effect balance out the increased incentive to pass on those hands that you are presented with a double in situation 2? It would I think be coincidental in the extreme if the two opposing factors exactly balanced out, and the issue is complicated by the fact players will make a takeout double with less than ideal distribution, but to differing extents.
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Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

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#2 User is offline   dogsbreath 

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Posted 2004-May-22, 06:23

Hi monacled one .. ;)
For me, there are other factors to take into account that you didnt mention. There is an old 'maxim' which says that if you dont X opps into game occassionally, then you arent doubling often enough .. i guess that just translates into the opinion that an aggressive approach to the game is winning bridge in the long run.
Factors I take into account are ...
1: my partener.. if you play in games with players of wide-ranging ability as I do in
'live' bridge, I dont like to make marginal doubles with inexperienced players..
it puts them under unnecessary pressure and disturbs their confidence when it
goes wrong.

2: If p makes a t/out x you should take-out unless it's absolutely clear-cut to
convert to a penalty x. I dont want to discourage my p's from competing, and
the opps dont always get subsequent auction right anyhow.

3: if opps get to 'know' you as a non-doubler they will take advantage and put you
to the guess even more often.

4: If i'm on lead ..is there a clear line of defence? .. ie: trump lead, forcing
defence or passive play?

Someone will undoubtedly post the maths about loss/gain from penalty doubles of part-scores which is a good basis but not always easy to judge at the table.
Regards, Dog :(
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#3 User is offline   the hog 

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Posted 2004-May-22, 06:28

Damn Eyerish spelling, you eedjit! Its monocled, not "monacled" or manacled. He's not into bondage.

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#4 User is offline   mikestar 

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Posted 2004-May-22, 07:32

The level must be taken into account. 3 of of suit is a much better prospect than 2 of a major, and 4 of a minor is better yet (though rare) for extracting penalties. In To Bid Or Not To Bid Larry Cohen suggests "With four trumps consider making a penatly double." (Intending this advice for primarily the three level and above).

Monocled One's analysis of the two situations is correct--you will leave in a takeout double at this level more often than you will make a penalty double.

An extreme example:

Neither side vul, the auction is (3S)-X-(P) to you and you have xxxx xxx xxx xxx. You place partner with 1-4-4-4 for total trick analysis. They have 8 trumps and we have 7, for fifteen total tricks. If they make, you are down 4. Leaving in is -530, taking out is -800. Even if they make an overtrick its -730 vs -1100. On the other hand, if partner has a strong double and they go down, the profit is obvious.

This can go wrong if partner is seriously off shape (in which case he will be strong and they probably go down, but you might miss a game) but it looks like the percentage action.
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#5 User is offline   mishovnbg 

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Posted 2004-May-23, 04:20

I am fan of optional doubles, esp vs modern in Europe overcalls with garbage and variable preempte with 5 cards... You can read here:
http://bridgebase.lunarpages.com/~bridge2/...findpost&p=4924

You can also track in "My hands" how many successful doubles of this type we did with Boian (PPilot). Of course to do that you need good hand evaluation and good level of defense... But without them you can't win either. Need to say when opps know about they receive almost any possible penalty double, they become far less aggressive and his play - less wining :) .

Misho
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#6 User is offline   dogsbreath 

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Posted 2004-May-23, 06:51

Hi Ron ;)
I've played -v- One-eyed and i suspect he plays better when subjected to some form of abuse ..maybe i should have used 'manacled' . :)

Rgds Dog

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