Scoring

[pirate22]

Can any one explain at IMP's a contract of 3n/t +1 freely bid,despite for examle a known 5/4 fit in spades or hts scores the same as 4s or 4 hts making

620 V 630---is there a reason and does this apply to matchpoints, although i never play MP-is it possibly to do with a possible defence-that 4h/4sp is 100% and 3 n/t can be held to 9 tricks???

[TylerE]

10 pt differences to do not score at IMPs...period.

[Finch]

At matchpoints there is a huge difference between +630 and +620.

At IMPs a 10-point difference makes no difference at all.

 

As for why a pair might bid 3NT with a 5/4 spade fit, I can think of three reasons off-hand:

 

1. They thought they were playing matchpoints, or point a board (BAM)

2. They didn't realise they had a 5/4 spade fit, because they had forgotten their system, or misbid, or not seen the auction properly

3. They thought 3NT might be more likely to make. Perhaps the hand was something like this:

 

[hv=n=sj542hkq3dj102cj102&s=sakqxxhaj10dq9cq93]133|200|1♠ - 2♠

2NT - 3NT

P[/hv]

[Old York]

At Imp scoring, you are rewarded for bidding games, especially vulnerable games, but it is not realy important which game you may choose to bid, except that you should normally choose the game contract which is most likely to make.

This might mean bidding 5-minor contracts more often, and 3NT contracts whenever you have sufficient points. The main point is that at Imps you look for safety first. "Bid boldly, Play safe" (Rixi Marcus) so bid most borderline games.

 

At Matchpoints, you must try to outscore your opponents who are bidding the same cards. The gain of 10 points can be huge if 3NT and 4♠/♥ are both making 10 tricks, but the major suit contract is preferred if you can score extra ruffing tricks, so shortages in dummy are essential. Bidding borderline games is not as important unless you think most others will be bidding it.

 

Tony

[xcurt]

A real hand, playing IMPs:

 

xxx

AKJx

xxx

AKx

 

P-P-P-1NT

P-2D!-P-2H

P-3NT-P-?

 

As it happened partner was 5-5 so bidding 3NT was quite precipitous. But if he has a balanced 9 or 10 count, do you really think you can make 4H?

[JavaBean]

The question is a little vague: are you asking why you might choose to avoid an 8-card major fit? At IMPs, Frances's example is a perfect one: there are 9 certain tricks, 4 top losers, and nothing useful to ruff, so a notrump contract will surely be better.

 

More generally, at IMPs it is better to bid the safer game, and at matchpoints the higher-scoring one. A lot of players read this as: at matchpoints avoid 5m, and consider avoiding 4M when 3NT might take as many tricks. But often the reverse is true: avoid 3N if 4M might take more tricks. For example: (sorry, can't make the diagram buttons work)

 

KJ98

JTxxx

x

KQx

 

AQT

9xx

AKxx

Axx

 

3NT is laydown, but you'll make only nine tricks on a minor-suit lead. In 4♠, you have several chances to make ten tricks. None of those chances are guaranteed, though, and if the opponents manage to defend well on an unfavorable layout you will go down. The odds are a bit too complicated for me to analyze, but it certainly looks better than 50%, so I'd want to be in 4♠ at pairs. At IMPs, however, 3NT is certainly best.

[Jlall]

9 tricks are easier than 10

[kenrexford]

The "asnwer" is that this is how we keep score.

 

If there was some bizarre bonus for something completely absurd, we might all shoot for that. For example, if the score for a contract 3♣ making exactly four somehow resulted in a bonus of 500, then people might bid 3♣ more frequently, with interesting declaring and defense problems arising, like intentional trick loss and counters to the same.

 

Actually, that concept might have some interesting permutations, such as if there was an additional penalty (like in some games) for "underbidding." If overtricks cost more than lost opportunity, but actually resulted in negative points, then the defense could actually launch a counter-intuitive lose-tricks defense, and Opener as well, with counters all over the place.

 

Suppose, for example, that 3♣ making four yielded +110 (for making 3♣), but -50 for the overtrick, netting +60. Two overtricks might reduce an additional -100, for a net of -40. The defense, then, could switch tactics to a sabotage defense.

 

Strange situations might develop, where Declarer gets caught in a situation where he can never get the exact 9 tricks contracted for but will either take 10 on one line or face only 8 with the counter-strike. Of course, he'd usually opt the overtrick, unless he missed the counter-strike option.

[Old York]

The "answer" is that this is how we keep score.

Suppose, for example, that 3♣ making four yielded +110 (for making 3♣), but -50 for the overtrick, netting +60. Two overtricks might reduce an additional -100, for a net of -40. The defense, then, could switch tactics to a sabotage defense.

Love the idea, can you patent it?

 

On the theme of scoring, I would like to see larger slam bonuses and a higher score for minor suit contracts

 

If clubs and diamonds scored 25 points per odd trick, the game would be vastly improved

 

Tony

[BnBeever]

NEW SCORING METHOD PROPOSAL: Board-Weighted Percent Scoring.

 

Now that computers make scoring so much easier, why don't we combine the nice features of both MP and IMP scoring - more explicitly let's have a scoring system for pairs that gives a %, without declarers being clobbered for giving up the chance of an overtrick to ensure the contract makes. The system I propose is particularly useful for duplicate events with small numbers of tables, where matchpoints are almost meaningless.

 

Here are the details:

 

For all NS pairs, subtract the lowest NS score from theirs.

For all EW pairs, subtract the lowest EW score from theirs.

This will make the lowest scoring NS and EW pairs get 0.

Divide these adjusted scores by the highest adjusted score in their direction, and multiply by 100, to get a %. Call this P. For those concerned about possible division by zero (for flat boards), define P = 0 in these cases, though this problem goes away naturally, as it turns out (see next-but-1 paragraph).

 

As it stands, this unfairly penalises pairs who make game but don't get an overtrick, if every other pair foregoes the safety play and makes the overtrick. So to fix this, we define a 'board weight', as follows:

 

Find the range of NS scores (highest minus lowest), convert this 'score' to IMPs, then multiply this by the number of other results (i.e. 1 less than the number of results for the board). This is the board's weight - call this W. Clearly, a flat board has a weight of zero. Some may object to this, but if everyone gets the same score on a board, why should it be considered in assessing someone's score? On some boards, any sensible line results in the same number of tricks; does scoring the same as everyone else on such a board mean you are a 50% player? I would say it means nothing. This also avoids worries about defining P for flat boards.

 

A pair's final % is the sum of P x W for each of the boards they play, divided by the sum of the weights of the boards they played.

 

Now a quick point about IMPs. To make it easy to score without a computer, IMPs were defined as a step function of points scored, but with a computer we can reward scores much more accurately (as BBO does) by using decimals. There may be a formula for this somewhere, but I couldn't find it, so I made my own, which stays pretty close to the step function, though it slightly overvalues low scores.

 

IMPs = Log(1+Score/2)^2.6

 

I've written an Excel file that can be used to score events in this way. If anyone wants a copy of it, send me an email at benbeever@hotmail.com

 

The main problem with this method, as I see it, is how best to desensitize the scoring to extreme, freak scores. IMPing the scores before calculating their % is one way. Capping all scores at 500 pts above the 2nd placed score for their direction is another.

[babalu1997]

Beever

 

Could you elaborate on the impact of this scoring method on the bidding of a few of the major systems, like sa, precision or 2/1, for example.

 

These systems pefrom better or worse for different types of scoring.

[helene_t]

Lu, this has obviously no impact on bidding systems. It may have impact on how aggressive you should bid, e.g. you may need only 9.3 rather than 9.4 HCPs to raise 1NT to 3NT. But the definition of your 1NT opening will not change.

 

The system would be identical to MP if there are only two tables, and it would approach IMPs (in terms of strategy) when the number of tables becomes very large. For a moderate number of tables, it would be somewhere in between.

[BnBeever]

Helene - although the % scores for each pair would be the same as MPs when there are only 2 tables, the big improvement would be that a board where say 1 NS pair were in no-trumps (and scored 10 points more than the other pair in hearts/spades) would be worth relatively little, compared to the board where 1 NS pair made game whilst the other NS pair went off. This therefore mimics IMPs scoring even with a low number of tables.

[PhantomSac]

Helene - although the % scores for each pair would be the same as MPs when there are only 2 tables, the big improvement would be that a board where say 1 NS pair were in no-trumps (and scored 10 points more than the other pair in hearts/spades) would be worth relatively little, compared to the board where 1 NS pair made game whilst the other NS pair went off. This therefore mimics IMPs scoring even with a low number of tables.

Why is this an improvement?

[babalu1997]

Lu, this has obviously no impact on bidding systems. It may have impact on how aggressive you should bid, e.g. you may need only 9.3 rather than 9.4 HCPs to raise 1NT to 3NT. But the definition of your 1NT opening will not change.

 

The system would be identical to MP if there are only two tables, and it would approach IMPs (in terms of strategy) when the number of tables becomes very large. For a moderate number of tables, it would be somewhere in between.

i beg to disagree helene

 

acol and precision systems do work better in imps

 

2/1 and ks better at matchpoints

 

It also has an impact in defensive bidding agreements, if you read mike lawrences books on competitive bidding he always elaborates on different actions depending on scoring

 

 

i am not ken rexford, so i want to open a book and learn from that

[babalu1997]

Helene - although the % scores for each pair would be the same as MPs when there are only 2 tables, the big improvement would be that a board where say 1 NS pair were in no-trumps (and scored 10 points more than the other pair in hearts/spades) would be worth relatively little, compared to the board where 1 NS pair made game whilst the other NS pair went off. This therefore mimics IMPs scoring even with a low number of tables.

then if this thing is similar to imps scoring, then i think i will pass

 

i much prefer matchpoints games, i prefer the bidding, i prefer the defense, i prefer the card play

 

People who like imps have a lot more opportunities to play online that i have

 

 

me want matchpoints

[BnBeever]

Helene - although the % scores for each pair would be the same as MPs when there are only 2 tables, the big improvement would be that a board where say 1 NS pair were in no-trumps (and scored 10 points more than the other pair in hearts/spades) would be worth relatively little, compared to the board where 1 NS pair made game whilst the other NS pair went off. This therefore mimics IMPs scoring even with a low number of tables.

Why is this an improvement?

Well of course everything is a matter of taste, but it seems that 90% of BBO players would agree it is an improvement, as roughly this proportion play for IMPs rather than MPs.

[Dirk Kuijt]

This reminds me of my proposal from a few (OK, many) years ago.

 

Each pair's score is the IMP score vs. a zero par, so +110 gets you 3IMP. Of course if the board is flat then every NS gets +3 and every EW gets -3, so there is no overall effect. Equally, for any flat board, regardless of result, there is no overall effect, provided that one compares NS with NS and EW with EW.

 

However, if any pair has bid and made a small slam, the par score becomes the slam bonus (+500 or +750) instead of zero. If any pair has bid and made a grand slam, the par score becomes the grand slam bonus (+1000 or +1500) instead of zero or the small slam par.

 

In those extreme and rare cases where both sides have bid and made a small slam, then the par goes back to zero. Ditto for both sides making a grand slam (in your dreams). If one side bids and makes a small slam and the other side bids and makes a grand slam, then the par becomes the small slam bonus for the grand slam side.

 

The point of this scoring system is two fold. First, the effect of those weird sets where someone has been dropped in a redoubled cue bid is minimized. The two pairs affected have a strange result, but it doesn't change other effects much. Second, there is still a big incentive to bid and make a slam. Suppose one pair bids and makes a small slam in hearts, not vul. Then, that pair scores +980 and the par becomes +500. So, all the pairs in game score -20, or -1IMP. The slamming pair wins 10 IMP. If that one pair goes down, then they score -50 or -2IMP, while the game pairs score +450 or +10IMP. So, bidding a slam on a finesse is more or less 50-50, which is what my intuition says is right. (Of course, if someone bids and makes a small slam on three finesses and a suit break, when the sensible pairs are in game, then the slam bidders still win 10 IMP. This doesn't eliminate luck.)

[Vampyr]

Helene - although the % scores for each pair would be the same as MPs when there are only 2 tables, the big improvement would be that a board where say 1 NS pair were in no-trumps (and scored 10 points more than the other pair in hearts/spades) would be worth relatively little, compared to the board where 1 NS pair made game whilst the other NS pair went off. This therefore mimics IMPs scoring even with a low number of tables.

Why is this an improvement?

Well of course everything is a matter of taste, but it seems that 90% of BBO players would agree it is an improvement, as roughly this proportion play for IMPs rather than MPs.

Why aet up a system of matchpoints that mimic IMPs, rather than just playing IMPs?

[Vampyr]

So, bidding a slam on a finesse is more or less 50-50, which is what my intuition says is right.

 

What do you mean by "what your intuition says is right"? You don't need to rely on intuition; the percentage you need for slam can be calculated exactly at various combinations of form of scoring and vulnerability.

[helene_t]

Lu, you are making bridge much more complicated than it already is.

 

It is true that Lawrence (and everyone else for that matter) recommend more aggressive overcalls at matchpoints than at IMPs. And of course more aggressive balancing.

 

But that is when he is discussing borderline hands where several actions would be sensible and it's just that one action has a small edge at MP and a different action has a small edge at IMPs.

 

You won't lose much if you just simplify things by ignoring the scoring. Unless you are a top player, there is so much scope for improvement that is way more significant than scoring considerations.

 

Besides, if you play matchpoints in a weak field (and by weak I mean everything that isn't worth vugraphing on BBO), it becomes more similar to IMPs. This is because the frequency tables are likely to contain lots of different scores, so a difference of 10 points is likely to translate into very few matchpoints. Say you have a choice between

1) a 80% make and 2) a 60% make with an overtrick. In a strong field we have all learned that you go for the overtrick. In a weak field you might as well play safe since lots of other pairs will be in a partscore or collecting some 300 penalty or going down in a slam or w/e.

 

And even if you are a top player, you certainly shouldn't play different systems at different scoring.

[babalu1997]

Lu, you are making bridge much more complicated than it already is.

 

It is true that Lawrence (and everyone else for that matter) recommend more aggressive overcalls at matchpoints than at IMPs. And of course more aggressive balancing.

 

But that is when he is discussing borderline hands where several actions would be sensible and it's just that one action has a small edge at MP and a different action has a small edge at IMPs.

 

You won't lose much if you just simplify things by ignoring the scoring. Unless you are a top player, there is so much scope for improvement that is way more significant than scoring considerations.

 

Besides, if you play matchpoints in a weak field (and by weak I mean everything that isn't worth vugraphing on BBO), it becomes more similar to IMPs. This is because the frequency tables are likely to contain lots of different scores, so a difference of 10 points is likely to translate into very few matchpoints. Say you have a choice between

1) a 80% make and 2) a 60% make with an overtrick. In a strong field we have all learned that you go for the overtrick. In a weak field you might as well play safe since lots of other pairs will be in a partscore or collecting some 300 penalty or going down in a slam or w/e.

 

And even if you are a top player, you certainly shouldn't play different systems at different scoring.

i again disagree helene, but the question of systems perhaps should be moved to another thread.

 

Playing precision, open 1d, the guy has limited his hand, answers are changed.

 

Playing SA, his range is huge, let us say 11-18, answers are changed.

 

I get genereally better scires at matchpoints with 5 card majors and better at imps with 4 card majors even in the palooka field.

 

Sometimes i get an undeserved score in matchpoints because we were playing in a field of imps bidders, sometimes I get a few imps because the imps bidders were bidding game when they should not.

 

So i just try to figure out whether the bad score was the result of something partner and i did, and move.

 

i do not plan to graduate from the free tourneys and go play the reisinger, so it is ok.

 

As for scoring, why change it?

 

the 90 percent who like imps will and do open their own tables.

the tds whose 90 percent of membership prefer imps are free to set their tourneys as they wish.

 

Let them do so.

 

As for me, ourt experience has been, when we sit at the main club and open a matchpoints table, we get much much better opposition than when we open imps.

 

Matchpoints scares many a bbo expert.

 

Very few people still play rubber bridge at bbo, why not change the scoring and compare with some par value so that the imps bidders can now enjoy a rubber scoring table?

 

I say that the folks who like to play rubber bridge find each other, mark each others names and life goes on...

[helene_t]

I get generally better scores at matchpoints with 5 card majors and better at imps with 4 card majors even in the palooka field.

Funny, I think most would say it's the other way round.

 

5-card majors is generally better than 4-card majors for slam bidding (except when you open a minor suit and opps preempt over it) which is a bigger edge at IMPs than at MPs.

 

4-card majors lets you find your 4-4 fit faster which is especially an advantage in part score battles, and sometimes the less revealing auction gives you an overtrick. Of course the 4-card major openings can also sometimes mess up opps' constructive bidding, and the less revealing auction sometimes allows you to make an unmakable game contract.

 

Lawrence wrote in his 2/1 workbook that he thought the pros and cons of 5-card majors roughly cancel each other out for all purposes other than slam bidding. If he is right, everyone should play 5-card majors, but if you find 4-card majors more fun and easier to learn you would be more likely to let that be decisive and not bother learning 5-card majors if you mainly play matchpoints.

 

the 90 percent who like imps will and do open their own tables.

Yeah I wonder why as I personally prefer matchpoints. To some extent it is just the fact that IMP is default and people don't make a conscious choice. But also I think IMP is more prestigious in some circles because club games are usually matchpointed while serious competition is more often IMPs.

 

Very few people still play rubber bridge at bbo, why not change the scoring and compare with some par value so that the imps bidders can now enjoy a rubber scoring table?

IMPs and matchpoints are similar in that most decisions will be the same - it is only in borderline cases that one action has an edge at MPs and the other at IMPs. Rubber bridge is a completely different game. Say you need 60 points to reach the rubber, then you may just open 3♦ with 18 HCPs. Or raise partner's 15-17 1NT opening to 2NT with 14 HCPs. Or pass partner's 2♣ response to 1NT when you only need 40 points - you probably shouldn't play Stayman in that situation.

 

Most club players barely know the difference between MP and IMP strategy but they can play adequately anyway. Some experts have wicked ideas about matchpoint strategy too, IMHO, but of course I could be the one who is mistaken :P People who play rubber bridge without knowing the difference between rubber and IMP strategy would do completely absurd things all the time. Like raising a 2NT opening to 3NT when they only need 70 points for game.

 

Sometimes i get an undeserved score in matchpoints because we were playing in a field of imps bidders, sometimes I get a few imps because the imps bidders were bidding game when they should not.

You get the "undeserved" score because some people in the field make silly mistakes. It is very unlikely to be related to the scoring.

Say your p bids an invitational 2NT. You are vulnerable and you judge 3NT to be 45%. So you would have accepted at IMPs but you decline because it's MP. Then you see than some people in the field have bid 3NT and went down.

 

First of all, if the chance was really 45% then this will work against you 45% of the time so the edge is small. But more likely, something else happened:

- given the info that the other players had, the chance was actually 60% so they were right in bidding it but were just unlucky (or played it badly).

- given their info the chance was actually 30% so they shouldn't have bid it anyway, even if they thought it was IMPs.

[hotShot]

The main difference between MP and IMPs is that at MP each board has the same weight. A boring flat board has the same weight that a close slam makable only on a triple squeeze.

Many good player prefer IMPS at BBO because they can score many points at difficult boards, and can relax during the simple ones.

Many average player prefer IMPs because a lucky board can help their score a lot, while at MP the sum of small losses has a much bigger weight that their good board.

 

BBO uses XIMPs. They are closer to MP than simple IMPs.

[helene_t]

BBO uses XIMPs. They are closer to MP than simple IMPs.

What do you mean by "simple IMPs"? Butler?

 

XIMPs is similar to Teams. Butler is a little different.