[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]

Cthulhu D, on 2014-December-11, 05:40, said:

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]

Vampyr, on 2014-December-11, 08:04, said:

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]

mgoetze, on 2014-December-11, 12:36, said:

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]

mycroft, on 2014-December-11, 15:31, said:

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

Quote

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]

akwoo, on 2014-December-10, 15:53, said:

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. You are saying that a 67% solution isn't as good as a 70% solution. Congratulations, you must have gotten a passing math grade

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]

Cthulhu D, on 2014-December-11, 17:39, said:

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.

[awm]

The hands where correcting to a minor helps you are in a pretty narrow range. After 1♣-1♥-1♠ you need all of:

1. 2533, 3523, or 3433 shape.
2. Either doubleton spade, or enough strength that passing 1♠ is not an option.
3. A weak diamond holding.

Even given all of this, if partner has strength in diamonds you could be better off a trick lower in notrump. And if you do in fact have 2-3 weak diamonds opposite weak diamonds in partner's hand, there is a decent chance the opponents would have bid diamonds in the auction. And even after all that, 2m doesn't always play better (i.e. sometimes you just have seven tricks, especially since the shapes above don't offer much in the way of ruffing values). 1NT is also more difficult to defend (especially when opener can be balanced, making opener's minor a very possible opening lead).

It just seems like you need a lot of things to happen, and my experience is that this sequence of events is pretty infrequent, certainly much rarer than missing a 4-4 spade fit and getting an inferior result in 1NT after bypassing on a balanced hand.

[mycroft]

Quote

You are saying that a 67% solution isn't as good as a 70% solution.

No, he is not - he is saying that a particular 55% system for a 50% player is a 67% system for a 70% player(*). Sure he cherry-picked his numbers; but roll your own, and you'll see that your original suggestion - that if there's a better system out there, it is in the interest of the best card player in the field to be playing it as opposed to both playing the field system and encouraging homogeneity - is simply not a given. It is *almost always* in someone's best interest, if they're sufficiently strong in one thing, to minimize variance in everything else.

(*) So, is it better? It turns the expert into less of an expert, but it makes Joe and Jenny Average into potential winners every club night! Of course, that depends. Are you a top 1% card player, or are you Joe or Jenny Average?

[akwoo]

Look - I'm a pure mathematician, and interested in theory.

I agree in practice these differences are just far too small and the confounding factors far too large to actually tease out from data.

I think it's clear from my example that whether a system is superior or not for you can, at least in theory, depend on how good a card player you are.

You can say you're not interested in theory. But then this whole discussion is moot anyways. The difference between any two reasonably good systems played by good bridge players who understand the systems is basically impossible to reliably tell apart in any reasonable amount of practice unless you're playing 50 boards every day and keeping careful records.

[mikeh]

mycroft, on 2014-December-11, 22:16, said:

No, he is not - he is saying that a particular 55% system for a 50% player is a 67% system for a 70% player(*). Sure he cherry-picked his numbers; but roll your own, and you'll see that your original suggestion - that if there's a better system out there, it is in the interest of the best card player in the field to be playing it as opposed to both playing the field system and encouraging homogeneity - is simply not a given. It is *almost always* in someone's best interest, if they're sufficiently strong in one thing, to minimize variance in everything else.

(*) So, is it better? It turns the expert into less of an expert, but it makes Joe and Jenny Average into potential winners every club night! Of course, that depends. Are you a top 1% card player, or are you Joe or Jenny Average?

This entire discussion has left me feeling bemused.


1. There is no such thing as the 'field' method, even if every pair in the room were playing the same convention card. In the typical mp field, outside of a few select events, there are so many pairs of such varying skill and understanding that even tho two pairs my 'play the same method', they will frequently bid hands quite differently.

2. There is a huge difference between the notion of playing a 'different' method than the field is playing and that of playing a high variance method.

In my partnerships, when we play Regionals, or Sectionals or club games, we play methods very much more complex than the field does, and with different notrump ranges, transfer walsh, transfer advances, meckwell, and other devices few if any others play. These are not in my view 'high variance' methods because while they do often result in non-field contracts, such contracts are almost always better, and often much better, than the 'field' contract.

if your methods reach inferior contracts even half as often as they reach superior contracts, change your methods!

Math based on the notion that the expert method will reach bad contracts, compared to the field contract, a significant amount of the time reveal that the mathematician doesn't understand expert bidding. Expert bidding is not aimed at randomizing results in the hope or expectation that for every bad contract two good ones are reached. Expert bidding is designed to avoid the bad contract just as much as it is designed to reach the good one.

[awm]

akwoo, on 2014-December-11, 22:54, said:

I think it's clear from my example that whether a system is superior or not for you can, at least in theory, depend on how good a card player you are.

This is true in principle, but in reality I think it's greatly overrated. First, most people are interested in playing events where they are fairly close to the level of the field, so a lot of the examples where you are much better (or worse) than the average are not typically events people care about (maybe the qualifying stages of a large event, but if you're so much better that you "rate" a 60+% just on card play your chance of failing to qualify due to a randomizing but not greatly inferior system will be minute). Second, a lot of crazy things happen on bridge hands -- "the field" is not making the same decisions even if they play the same system, and opponents may do crazy stuff at other tables. The extra trick that you find through good play might have just been given away by bad defense at many other tables! Third, the superior card-play advantage will pay when you are in non-field contracts too, so the slam that's only 55% and that no one else bids may be 90% given your superior declarer play and the opponents' inferior defense.

In general I think it pays to bid the superior contracts and not worry too much about what "the field" does, since the field will be far from unanimous and is often hard to predict.

[jdeegan]

mikeh, on 2014-December-08, 18:11, said:

As is usually the case, the people who advocate one style are quite good at pointing out the merits of their style but reveal their ignorance when they claim to set out the pros and cons of the opposite style. I am not suggesting any intention to mislead...this is just human nature. We tend to see reasons why we do what we like to do, and to ignore reasons for doing something else.

So it is with some sense of the irony inherent in my now posting on this subject that I write my views....the foregoing may well apply to me!

.

Thanks for a really good lesson on the merits and demerits of rebidding 1nt with 4♥ or 4♠ or even both. I have noticed top level players doing this, at IMPs, for some time and wondered. In essence, the idea is that defining your hand as a weak NT opener (both a limit bid and showing shape) is more important than showing your major suit(s). Makes sense to me, I think. Hard to break old habits, though.

Usually, responder will not bid 1♦ holding a 4 card major with less than 10 HCP. Consequently, the window for 1NT getting passed out when a 4-4 major suit fit is available is small. On the other hand, a fair percentage of such hands will offer good plays for game. So, maybe I am becoming a Walshite at last. Never bid 1♦ over 1♣ holding a 4 card major unless you have at least a game try opposite a weak NT opener.

[akwoo]

mikeh, on 2014-December-11, 23:20, said:

if your methods reach inferior contracts even half as often as they reach superior contracts, change your methods!

There are methods where the causes of reaching inferior contracts are the same as the causes of reaching superior contracts (particularly for low level part scores). You can't get rid of one without getting rid of the other.

For an average-ish player like me, I would love a system where I reach an inferior contract half as often as I reach a superior contract! (Actually, as a low-to-mid-50s player still eligible for lowest stratum masterpoints, it's masterpoint-maximizing to have almost as much variance as I can get, with or without an increase in expectation.)

I don't think this discussion is moot. I think Meckwell have pretty much said that they abandoned the mini-notrump because of the high variance, even though they still thought it resulted in a better contract more often than it resulted in a worse contract.

I think variance is one of the big reasons there is so little weak NT or mini NT in the US.

awm, on 2014-December-11, 23:25, said:

In general I think it pays to bid the superior contracts and not worry too much about what "the field" does, since the field will be far from unanimous and is often hard to predict.

I agree in general, but for any specific system there are a few spots where there is a common anti-field difference that you might accommodate. For example, playing a 12-14 1N opening in an MP game, I always bid 1♥ in response to partner's 1♣ opening with something like ♠xxxx ♥Kxxx ♦Jx ♣xxx even though I seriously doubt that it gives a better score than passing more than half the time. It's just that, basically due to the field system being 15-17 1N openers, I'll lose a lot more when passing is wrong than I'll gain when passing is right.

[johnu]

akwoo, on 2014-December-12, 01:34, said:

I think variance is one of the big reasons there is so little weak NT or mini NT in the US.

I think most players in the US would have trouble spelling variance, let alone understand the theory. Almost everybody plays strong NT in the ACBL because that's what the bridge instructors and popular bridge books teach. It's not as simple as saying let's play weak NT's because all sorts of auctions need different interpretations and most players are not equipped to do it on their own, even if they had any interest in trying something different.

[helene_t]

awm, on 2014-December-11, 23:25, said:

In general I think it pays to bid the superior contracts and not worry too much about what "the field" does, since the field will be far from unanimous and is often hard to predict.

While I agree with this in general, I also think that the particular auction we are discussing here is close and you can't call either method superior.

Then again, where in the world can either method be called the field method? In England, most will bypass but then again many would have opened 1sp in the first place or play a different nt range. Besides, when both opps have had the chance to bid at the onelevel I wouldn't assume that the field is having an uncontested auction. In the Netherlands I wouldn't be sure that the field would get a 1he response as people play different responses to 1c. Finally, even if you find the field rebid, this is a situation in which responders will make different choices at their second turn. Different check back structures. Some can't pass 1s because it's forcing to them. Some like bidding nt even without a diamond stop.

Something else: I think bypassing is easier and would recommend that to intermediate players. Fsf auctions are awkward if opener only clarifies his balanced hand at his fourth turn. And you need a check back structure anyway.

[jallerton]

helene_t, on 2014-December-11, 06:31, said:

(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.

Obviously inferior if you could guarantee an uncontested auction. When you factor in giving the opponents an extra step after the frequent major suit showinf responses, it's not quite so clear.

(Not everybody can resist temptation like you.)