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How to tackle the 'rogue 7NT' bidder?

#1 User is offline   661_Pete 

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Posted 2017-January-11, 17:46

This is a constant nuisance for those of us who take our participation in BBO reasonably seriously (monitor our IMP average and strive to improve it, I mean).

Not because of such a player turning up at our table. After all, for misbehaviour of that kind they would surely be ejected by any responsible host.

Instead because of the distorting effect they can have on other tables which have played the same hand.

I've noticed this sort of thing several times, and as it happens there was one in today's play, although this time it worked to my partner's and my advantage, so I suppose I shouldn't be complaining! Nevertheless, if we gain, our opponents lose, and I don't like to score against decent opponents (good players both) on these terms. I'd rather score because of honest play.

Sitting East-West, we were in a good 3NT contract, well bid and made. mostly thanks to my partner's good play ;) , and earned a top on the board. What surprised me was that we netted over +11 IMPs on the hand, more than you would expect for a simple 3NT, so I looked at the traveller. And sure enough, on one table another E-W pair had gone 1NT-7NT, totally unwarranted and presumably out of bloody-mindedness. Whatever, this little excursion bagged that pair -8.5 IMPs and pushed all the other E-W scores up by a substantial margin.

This is not as bad as the alleged cheating which lots of BBO players have been complaining of, of late. But it is still annoying.

Should there be zero-tolerance of that sort of behaviour? After all, it is easy enough to spot and report - unlike cheating.
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#2 User is offline   hrothgar 

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Posted 2017-January-11, 17:51

View Post661_Pete, on 2017-January-11, 17:46, said:


Sitting East-West, we were in a good 3NT contract, well bid and made. mostly thanks to my partner's good play ;) , and earned a top on the board. What surprised me was that we netted over +11 IMPs on the hand, more than you would expect for a simple 3NT, so I looked at the traveller. And sure enough, on one table another E-W pair had gone 1NT-7NT, totally unwarranted and presumably out of bloody-mindedness. Whatever, this little excursion bagged that pair -8.5 IMPs and pushed all the other E-W scores up by a substantial margin.



Does the number that BBO tells you a board is worth matter a damn?

If you actually care about this, simply rescore the hand yourself and mentally award yourself the score that you actually deserve.
If you don't care, all the better. You don't need to do anything.
Alderaan delenda est
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#3 User is offline   GrahamJson 

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Posted 2017-January-13, 10:10

A simple remedy, at least for the scoring aspect, it for BBO to adopt Butler scoring. In this the top and bottom scores for a board are ignored and the remainder are averaged. This eliminates bias caused by one extreme score. I believe that if the board is played many times the top and bottom two scores are not used when calculating the average.

http://www.bridgeweb...rgh/page14.html
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#4 User is offline   mycroft 

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Posted 2017-January-13, 11:34

There are massive issues with Butler scoring:
  • the datum (that average you are talking about) is almost never a bridge score, and the IMP scale relies on bridge scores for a lot of its boundaries (never mind that there's no spot on the IMP table for a 43 difference, frex). This means unrealistic comparisons. It also means that a change in the score in your benefit (from -140 to -110, for instance) may in fact *reduce* your IMP score, if it changes the datum sufficiently (there's a well known example from a high level cash-prize tournament).
  • compared to the "blow off" 7NTxx hands, the number of hands where an extreme score is actually valid (Oh, I'm the only one playing Precision, so I'm the only one that can find the grand; my opponent refuses to sit still and took the -2300 sac of our 6 contract; Cappelletti mixup leads to 3-4 on the 4-1 fit or 5x-4 if bidder panics) means that we shouldn't magically "throw them out". Sure, *they* get their result; but I get an automatically better score than I would because I don't have to score against the Precision grand bidders.
  • because of the nature of throwing the scores out, the total result on a board/session is never zero. If you happen to be on the side that averages -23/18 board session, is that not as much of a bias problem as the blow off 7NT?
  • Of course, datum doesn't work at MPs...


I'll deal with the 7NTxx-10 hands the one time a day I play against one to avoid all that nonsense. Please let's never go back to that distorting, wrong, easy-to-score-by-hand but we haven't done that since 1990 method of scoring.
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#5 User is offline   barmar 

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Posted 2017-January-13, 13:27

Butler scoring was a crutch in the days when bridge was scored by hand, since calculating all the cross-IMPs was extremely tedious for humans. It has no place when games are scored by computer.

Really, you should just ignore the effect of the 7NTxx hands, since it affects all the pairs playing the board equally. All that matters is your relative score among your peers, not the absolute number.

#6 User is offline   1eyedjack 

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Posted 2017-January-13, 14:00

If 15 out of 16 tables make a routine game (including at your table), and one (other) table plays in 7NXX 4 down, then against that table in isolation you are looking at about a +/- 20 imp swing depending on vul etc.

In terms of your average IMP score for the traveller you are looking at about +/- 1.3 IMPs.

Then if you consider its significance over a month of about (say) 250 hands (typical for the OP) its impact on your average score is about 0.005 IMPs.

Bottom line? Don't let it get to you.

Butler scoring does not solve the problem. It eliminates the 1.3 IMP aberration but at a much greater cost on the vast majority of other hands where everyone plays to win. Furthermore, Butler scoring has absolutely no effect on mitigating the problem of the scores of the players at the table where the offense happens.
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#7 User is offline   johnu 

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Posted 2017-January-14, 04:40

View PostGrahamJson, on 2017-January-13, 10:10, said:

A simple remedy, at least for the scoring aspect, it for BBO to adopt Butler scoring.


You don't need to use Butler scoring. You could also drop out a couple of extreme score comparisons in the cross imp scoring that is used and accomplish the same thing.
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#8 User is offline   mycroft 

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Posted 2017-January-16, 10:29

True, we could cross-IMP against almost all the results. But that only kills off the problems with the datum (increase in my score may decrease my IMP result, datum is not a bridge score). It might even kill the "but at MPs" - I'd have to do the math, but I'm guessing it would still zero out.

However, it doesn't resolve the (much more common) issues that the extreme scores are valid (issue of the last tournament was whether, due to use of UI, -1100 at the table should have been -1400 or -1700; into -430 at the other table! Now do I feel bad if I don't get to score against that result/feel good that I don't have to score against that result - at the other tables?) and that because those extreme scores *compare*, the result on a board is never zero, and if the bias goes all in one direction (it was usually about 4-5 IMPs one way back in the datum days, but occasionally it was 25, 30) is that fair to the players sitting the other direction?

What if the ghost of Barry Crane is sitting E-W? ("Why did Barry Crane not score as well at IMPs than MPs?" "+5, +5, +5, -17") Or the FP pair? Or, as I said in my last, the player who just will not be preempted, and bids all 52 cards when taking sacrifices?
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