[VixTD]

 Siegmund, on 2015-November-17, 12:20, said:

There isn't, there is, and it isn't.

Whether IMPs or matchpoints, only comparing 2 results leaves twice as much variation in the final scores as comparing a large number of results does. More comparisons is better.
IMPs and matchpoints remain different games, in the same way, whether there are 2 comparisons or many.

It's not clear to me exactly what you're disagreeing with, Sigmund, but it seems to be everything.

I thought it was self-evident that the fewer tables you have the fewer score comparisons there are using any across-the-field scoring method.

When I said that your result on a board has more chance to "count" in the final scoring method when there are few comparisons (when there's a small field) if you are scoring by cross-IMPs rather than matchpoints what I meant was something Campboy alluded to earlier. If there's only one other table in play your result has only two chances to register any matchpoints: (i) if it matches the opponents' score, and (ii) if it is greater than the opponents' score. At cross-IMPs if your opponents get an unbeatable score at least your good efforts get some reward for reducing the score deficit on the board.

[Stephen Tu]

 VixTD, on 2015-November-19, 09:23, said:

When I said that your result on a board has more chance to "count" in the final scoring method when there are few comparisons (when there's a small field) if you are scoring by cross-IMPs rather than matchpoints what I meant was something Campboy alluded to earlier. If there's only one other table in play your result has only two chances to register any matchpoints: (i) if it matches the opponents' score, and (ii) if it is greater than the opponents' score. At cross-IMPs if your opponents get an unbeatable score at least your good efforts get some reward for reducing the score deficit on the board.

It may "count" in terms of your raw score for an individual board being altered. But at the end of the day, in terms of your overall score and overall ranking, these imps hardly matter at all. So it "counts", yet it doesn't really count in the end. It's like you are concerned about what comes out to rounding errors when total score for the evening is computed. And it renders a lot of boards where big swings aren't possible relatively meaningless.

At IMPs, your careful play to set up the double squeeze for the 2nd overtrick on board 2 counts 1/13th as much as the opps bidding slam on a finesse that happens to work on board 1. At MP, your good play has evened up the game. At IMPs you are still way behind.

Opps get a gift 800 on a partial board. As a good player, what would you rather have, a chance to lose 12 imps instead of 14 because your play on this board "matters", or a chance to recover the entire deficit with just an overtrick with good play on the next board?

IMPs basically renders a lot of boards very unimportant, because realistically only can have a 1-2 imp difference depending on how well played/defended the board is. While some boards have +/-13 imps in play, 26 imp swing vs. 1-2, sometimes simply on the result of whether a 50-50 finesse works or not. If you come up on the wrong side of that, it wipes out better bridge played on many, many other boards.
IMPs is just a board importance magnifier vs. MP. It's true that as barmar said that over 24-26 board pair session you have more of a chance to recover than over a 7 board Swiss match (more boards > fewer boards in evening out luck), but MP is way better still, as you only need one board to recover from a bad result.

MP is just less luck oriented than Imps. X-imp pairs is simply the most random kind of game in bridge. Teams has less luck than pairs because you have control at both tables. But Imps makes some boards worth much more than the others. It makes superior play in the form of extra overtricks/undertricks worth very little vs. what they are worth in MP. Basically from least luck to most luck is team MP > team IMP > pairs MP > pairs IMPs. Imps is just easier to play because you know what your goal is (beat/make contracts), and you don't have to stress over every single trick quite as much when it's clear the contract is making.

[Siegmund]

I think it is also self-evident that the considerations in a IMPs vs MPs decision are exactly the same in any size of field.

In a large field, a serious MP error will cost you the whole board and a small error will cost you a few matchpoints.
In a 2-table field, a serious MP error will almost always cost you the whole matchpoint and a small error will sometimes cost you the whole matchpoint . The relative sizes of the two errors remain the same, in terms of expectation, it is just harder to see when you only have one comparison.

Similarly, you will see some boards at IMPs that cost you 0 IMPs on a good day and 12 IMPs on a bad day when there is only one comparison, but cost you about 6 when there are a bunch of comparisons and half the field beats the game.

Maybe your players like IMPs in small fields... I just don't like small fields, and shake my head in amazement at the popularity of team games with only 2 comparisons when a lot more are available.

[barmar]

 Siegmund, on 2015-November-19, 10:27, said:

In a large field, a serious MP error will cost you the whole board and a small error will cost you a few matchpoints.
In a 2-table field, a serious MP error will almost always cost you the whole matchpoint and a small error will sometimes cost you the whole matchpoint . The relative sizes of the two errors remain the same, in terms of expectation, it is just harder to see when you only have one comparison.

That's what we call "field protection". In a large field, you can expect that you'll have some company in a small blunder. If the hand hinges on a 50-50 guess, you can expect half the field to guess right (scoring 75%) and half wrong (scoring 25%). But in BAM, you either get 100% (you guess right, opponent guesses wrong), 0% (vice versa), or 50% (you both guess the same) -- there's no field protection to smooth out the extremes.

[barmar]

 Stephen Tu, on 2015-November-19, 10:24, said:

IMPs basically renders a lot of boards very unimportant, because realistically only can have a 1-2 imp difference depending on how well played/defended the board is.

I think IMPs tends to be more oriented towards accurate bidding (especially game decisions), while MP is more about taking the maximum number of tricks in whatever contract you land in. The hands that tend to be unimportant at IMPs are the ones that are really easy to bid, since most pairs end up in the same contract,

[Stephen Tu]

 barmar, on 2015-November-19, 10:48, said:

I think IMPs tends to be more oriented towards accurate bidding (especially game decisions), while MP is more about taking the maximum number of tricks in whatever contract you land in. The hands that tend to be unimportant at IMPs are the ones that are really easy to bid, since most pairs end up in the same contract,

MP magnifies the importance of play relative to the bidding because overtricks/undertricks matter much more often. But MP also need very accurate bidding, to me it is harder to bid accurately at MP than at IMP. At IMP you just bid every game that's close, and with partials you just try to go plus, the strategy is pretty straightforward. At MPs now you have additional complications of choosing the right game or right partial, sacrificing way more often, doubling their partial way more often, having to make decision of whether to bid on to make sure you get +140 instead of +50.

Unimportant boards at IMPs are not only flat boards in terms of bidding, but also when the play/defense boundary randomly happens to be between overtricks or not instead of making or not.

I kind of view IMPs as a play accuracy on overtrick boards importance reducer. It's not a bidding accuracy magnifier, accurate bidding at MP is still crucial & harder in my view.

[gwnn]

 Phil, on 2015-November-16, 19:03, said:

2. People get depressed seeing negative imps but 46% won't faze them.

Why not start everyone from 1000 IMP's (call it "attendance bonus", say) and go down from there? Or however many it takes to keep everyone well into the positive?

[mycroft]

 Stephen Tu, on 2015-November-19, 10:24, said:

It may "count" in terms of your raw score for an individual board being altered. But at the end of the day, in terms of your overall score and overall ranking, these imps hardly matter at all. So it "counts", yet it doesn't really count in the end. It's like you are concerned about what comes out to rounding errors when total score for the evening is computed. And it renders a lot of boards where big swings aren't possible relatively meaningless.

At IMPs, your careful play to set up the double squeeze for the 2nd overtrick on board 2 counts 1/13th as much as the opps bidding slam on a finesse that happens to work on board 1. At MP, your good play has evened up the game. At IMPs you are still way behind.

But I don't understand. At IMPs, your careful play to set up the double squeeze for contract on board 6 counts 13 times as much as the opps guessing the two-way for the queen for the second overtrick on board 5. At MPs, your good play has evened up the game. At IMPs, you're massively ahead.

Quote

Opps get a gift 800 on a partial board. As a good player, what would you rather have, a chance to lose 12 imps instead of 14 because your play on this board "matters", or a chance to recover the entire deficit with just an overtrick with good play on the next board?

As a good player what would you rather have, a chance to go way ahead with a slam that for you is 70% rather than 50% on because you have the added bonus chance of the guard squeeze leading to the deadly throwin, or a series of boards that depend totally on whether you've "rightsided" the contract to avoid the killing lead that holds you to 4 instead of 5?

Yes, there are swing boards in IMPs and there are "flat boards" - but your play advantage doesn't *just* apply to turning the flat boards into small hills. It also turns your "flat boards" (say +/-2 X-IMPs) into 11+ IMP mountains.

MPs are maybe less luck oriented than IMPs - which is why the Reisinger is 3 days and the IMP primes are 7. But we're not talking about those games.

We're talking about games like this one:

• There's you and your partner. Solid, down-the-middle pair playing a pretty standard 2/1. However, your play is at or near the best in your area.
  
• There's me and my partner, playing K/S, and "wrongsiding" (as far as the search for the second overtrick vs totally different opening lead/leadthrough goes) all balanced 11-17s. But we play only at a reasonable flight A level.
  
• There's the pair that won't be preempted (yesterday went for 1700 against 1460 - and if partner had understood why I hit the sac (no first-round control in their suit) it would have been 2210 against 1460!), and bids everything in sight. "He plays at least a trick better than the field. Which is a good thing, because he's usually two tricks higher than the field."
  
• There's the "used to be good pair" one of whom is now losing it a bit. If North declares, you're getting a normal result. If South declares - or has the critical bidding decision - start throwing darts at the scoring table.
  
• And finally, there's the pair who play every convention you've heard of (at the same time, even if they conflict), but have never heard of control cue-bids or suit preference signals.
  
• Oh there's also a 5-board sitout.

Top on a board is 1, and you're scoring against one of the above 4 on every hand - which one? I can do the three-table Howell from memory, but even I won't do it at the table - and another of the 4 is their opponent (your "teammate" in the BAM scoring).

Still telling me that it will all boil down to fights for the extra overtrick? Still think that that is going to be more than "one more wave in the wash"?

Note that I'm not knocking matchpoints. Matchpoints is a fabulous game. It's not bridge, of course, but it's a fabulous game, and I love playing it.

[Stephen Tu]

 mycroft, on 2015-November-19, 13:09, said:

But I don't understand. At IMPs, your careful play to set up the double squeeze for contract on board 6 counts 13 times as much as the opps guessing the two-way for the queen for the second overtrick on board 5. At MPs, your good play has evened up the game. At IMPs, you're massively ahead.

But then there's another board that has a game swing on a two-way guess for the queen ... Why should so much depend on whether or not the extra trick is on a contract making or not boundary or the overtrick or not boundary? There are always some boards that depend on guessing & some that depend on skill. This is unavoidable. But with IMPs, you randomly select boards and make them way more important. If skill makes the difference, you are very happy if you happen to be in control of this on the big swing boards. But if it's just luck, or it's the other pair that has control because they have the cards, you are just totally screwed for like the entire game. You were defending, your opps are capable of finding the skilled play but the others weren't, there goes 13 imps, you can no longer win that day. At MP, you effectively get more sample size, there are way more boards that reveal skill differences, way more boards for the luck factor boards to even out. At Imps too many boards are relegated to +/- 1-2 imps while certain boards are 10+.

MP effectively tends to reveal skill differences in fewer boards. At Imps, if you play a large # of boards, the skilled players will come out on top just like at MP. But in a short club game of 24-27 boards, IMPs just arbitrarily picks a few of them and makes them super important. What would you think if say the NFL with its 16 game season, randomly selected for each team 2 particular games and made them worth 10 wins each?

Quote

As a good player what would you rather have, a chance to go way ahead with a slam that for you is 70% rather than 50% on because you have the added bonus chance of the guard squeeze leading to the deadly throwin, or a series of boards that depend totally on whether you've "rightsided" the contract to avoid the killing lead that holds you to 4 instead of 5?

As a good player I want as many boards as possible that give me a chance to pull ahead with skill, and many boards for the luck boards to cancel each other out. At MP my chances of getting sufficient boards is a lot higher than at IMPs. At IMPs I need to be lucky that the swing boards happen to be skill boards and under my control.

Quote

Top on a board is 1, and you're scoring against one of the above 4 on every hand - which one? I can do the three-table Howell from memory, but even I won't do it at the table - and another of the 4 is their opponent (your "teammate" in the BAM scoring).

Still telling me that it will all boil down to fights for the extra overtrick? Still think that that is going to be more than "one more wave in the wash"?

If there are lots of weird bidding going to be going on, things will get crazy at both MP and IMPs, and more boards are going to be won/lost in the bidding than in the play. But STILL, IMPs will put outsized importance on a few swingy boards. I don't see why it would ever be "better" than MP.

I think most people prefer IMP to MP because they prefer teams vs. pairs, and they associate team scoring with IMPs and pair scoring with MP. But I really don't understand anyone who prefers IMP pairs to MP pairs as it becomes more a crapshoot when the # of boards played is low. I prefer MP teams (aka BAM) to IMP teams also, as I think it's the purest skill test in the game, but it's very rarely run. Perhaps because of historical reasons, IMP scoring is closer to roots of the game in rubber bridge & total point team scoring. Plus the greater luck factor in IMPs giving more teams a chance to do well at least some days.

[barmar]

I think people prefer IMPs simply because it seems easier.

With MP, you often don't know what your goal is. If you're declaring, and the contract is in trouble, should you try to make it or just minimize your losses? When should you risk the contract to try to make overtricks? When defending, should you just cash out or try to set? During the auction, decisions about whether to sacrifice can be difficult.

IMPs generally feels easier. During the play, declarer's primary goal is to make the contract, defenders mainly try to set. Unless the contract is doubled, you don't worry too much about how many overtricks or undertricks are made. During the auction, decisions about sacrificing are generally easier.

[fromageGB]

 barmar, on 2015-November-20, 10:27, said:

I think people prefer IMPs simply because it seems easier.

Stephen Tu made the point that because things are much easier in IMPs, MPs rewards the skill needed to make the better decisions. Hence MPs is preferable if you consider yourself relatively skillful. Rather than play IMPS if you want a crapshoot, why not deal each board at each table and play total point aggregate but, in your personal total, ignoring any negatives? I came across this recently in a charity event that was misleadingly described as bridge.

[mgoetze]

 fromageGB, on 2015-November-23, 09:56, said:

Rather than play IMPS if you want a crapshoot, why not deal each board at each table and play total point aggregate but, in your personal total, ignoring any negatives? I came across this recently in a charity event that was misleadingly described as bridge.

Is there any reason to play a contract that is not redoubled at this form of scoring? That would certainly change the optimal strategy quite a bit...

[barmar]

 fromageGB, on 2015-November-23, 09:56, said:

Stephen Tu made the point that because things are much easier in IMPs, MPs rewards the skill needed to make the better decisions. Hence MPs is preferable if you consider yourself relatively skillful.

Even if I considered myself a reasonably skillfill tennis player, I still might not want to play against one of the Williams sisters. You don't always have to subject yourself to the hardest challenge, although admittedly the difference between ordinary and champion bridge players isn't quite as extreme as in physical sports (I've gotten occasional good boards against Zia, Larry Cohen, etc., but I probably wouldn't even be able to return any of Sampras's serves).

But there's a reason why they consider the Reisinger to be the hardest event on the ACBL calendar -- BAM is the most extreme form of matchpoints.

[mycroft]

I hate matchpoints - I love it too.

But Barmar's comment is why: "First thing you have to do when dummy comes down is figure out what the contract is." Part of what makes an advanced player such is that they have that theory internalised; part of what makes an expert is the ability to perform that work almost instinctively.

There are many good players who simply don't think of this - and it shows in their MP play. It applies in the bidding, too

Matchpoints also lends itself to luck: "Poker Bids are not Bridge and will be ADJUSTED". Well, actually...Matchpoint bidding can be a lot like poker. "if you've never gone for 800 playing DONT, quit playing DONT. Play a constructive system instead." or "well, 10% of the time their contract is going down, and 10% of the time we're going for 2K, and 10% of the time we're going to push them to a making 7, but the other 70% of the time, we're getting a good score for the sac. Now tie in the number of people we guess are getting there, and maybe we're just turning our zero into a slightly squarer zero, but still." or even "yeah, this overcall is going for 1400, but *they* probably don't know that, and I'll talk them out of the normal contract at least twice for every time they catch me speeding." or even "well, I'll make this 10% play because I'm getting a bad score if it's wrong and I don't do it, and turning 10% into 0% if it's wrong and I do do it and go down another 2..."

In general, I agree with you, Stephen, despite my comments. Matchpoints is a more skillful game than IMPs - and it rewards skill in the *play* even more - and skill will resolve faster at MP pairs than IMP pairs. But a 2.5 table "random club game" isn't "in general", by any means.

[barmar]

I think it's somewhat wrong to talk about the different forms being "more skillful". They each reward different skills (although they all require the same basics).

I suppose what you're saying is that the unique skills required to do consistently well at MP are more difficult to learn than those required for IMPs success.

[mycroft]

I do think matchpoints is a more skill, less luck game than IMPs. That's why the prime MP pairs/BAM team events are 3 days long and the prime IMP team events are 7-14. You just need more boards to reduce to the same amount of luck.

I do also think that MPs rewards different skills (and that those who are stronger players than the field like MPs, especially MPs in a one-true-bidding-style field) than IMPs.

I just don't think that any of this (besides "nobody told me we were playing IMPs", of course) matters much compared to the vagaries of the three-table random club game. I also think that "a game with more skill" is not necessarily an advantage to a club trying to keep a 3-table game from dying; "we go, D- and N- win again, whee." is a death knell for those.

Would I want to play in a crapshoot all the time? Of course not. But anything less than a 5 (10 UK) top in my experience will have sufficient elements of crapshoot that "which game is more skillful" is a low priority.

[Stephen Tu]

 barmar, on 2015-November-24, 10:16, said:

Even if I considered myself a reasonably skillfill tennis player, I still might not want to play against one of the Williams sisters. You don't always have to subject yourself to the hardest challenge

Doesn't bridge have enough game segregation already? Not up for Platinum pairs? There is a regional event on the side. Or bracketed KO. Or side pairs. Or 499er pairs if you aren't life master yet. etc. I still don't see why one would prefer IMP pairs over MP pairs; if you want easier game pick easier opponents. In any case, we are talking random small club game, it's not going to be the hardest challenge whether you score it IMP or MP. Pairs is already a game where it is mainly a question of how many gifts one can extract from the weaker opponents. IMP pairs just makes it even more random, it's how many gifts one can extract from weaker opponents *on the subset of boards where a big swing is actually realistically available*.

If I am up for an evening of bridge, even if I am only playing 2-3 table game at club against random opps, I still want as many boards as possible to "matter". This is going to be at MP not IMP. No matter what there are going to be some boards out of your control. At Imps, your actions might "matter" in terms of raw score on one board, but for your aggregate score the nature of IMP scoring is going to make a lot of those things basically not matter in the end anyway. At MP, a higher number of boards where your actions matter are going to materially affect your score, since each board is worth like 4% of your total. At IMPs it's like some boards are worth 0.5% and other boards are worth 8%. You can crush the opps on the 0.5% boards then they get lucky on the big board, and you feel like your placing doesn't really reflect how well you played.

I want to have to try on all 24-27 boards because I can't afford dropping tricks since who knows if they reached same contract at the other table or not. I don't only want 4 or 5 of those to matter since on the rest realistically one side is going to score up their partial or game and only overtrick or not is the issue, or for one lucky slam to dominate the placing of the entire evening.

[mgoetze]

 barmar, on 2015-November-24, 14:41, said:

I suppose what you're saying is that the unique skills required to do consistently well at MP are more difficult to learn than those required for IMPs success.

I think that's tangential to the argument, the point is that MPs have lower variance (because IMPs have arbitrary weighting) and thus your skills will translate into success more often.

[Vampyr]

 SteelWheel, on 2015-November-18, 16:12, said:

Here in ACBL-land, nothing about scoring any bridge game makes much sense to me.

For example, in local club games, the idea of scoring via any method other than matchpoints is virtually unheard of.

However, in most Regional tournaments, the (by far) dominant method of scoring for nearly all events is by imps (not x-imps, but imps nonetheless). And why is this? Because the product that ACBL sells is masterpoints.

Hence, nearly event is a "bracketed round-robin Swiss", where they just start cutting the field into seven or eight teams per bracket, and have each team play against all the others. After all, it awards more masterpoints, since each bracket rewards those precious gold points to at least three teams.

Heaven forbid that any pair play their best all day long in a matchpoint event and have "nothing to show for it". Must award gold points!!

I'm a lonely voice, I guess. I became a Life Master a long time ago, and it wasn't all that tough to get there, even under those old, draconian rules (y'know, the ones that required that you be able to beat LMs in order to become one?).

Modern tournament bridge is so deathly dull with the heavy emphasis on formats which will award the most masterpoints possible (NABCs mostly excepted). But hey, where is someone ever supposed to learn how to play matchpoints (vs a strong field), or IMP pairs, or (gasp!) board-a-match, if the clubs and the non-national tournaments don't put such events on the schedule?

ok, rant over. Go back to your normal business...

I became an ACBL Life Master way back then also, and I agree that tournaments were fairly interesting then; the big pair events were prestigious, and without the bracketed games the team games were big and important as well. I haven't played in very any ACBL tournaments in the last 20 or so years, but from what I have seen and read, I realise that everyone now is playing in side games and there are no big events anymore (apart from the very biggest). Perhaps if the ACBL reduced the masterpoint awards in bracketed games to be commensurate with other events, they could once again offer a varied schedule, even expand to events which are rare there, such as multiple teams or Swiss pairs. Oh well, sorry to carry on a discussion that is rather off-topic.

So I will try to make up for it: I think that IMP pair games of any size are poor, and it is a pity that the best (Friday night) games around here are all scored that way. What if small games used some sort of instant-matchpoint scheme?yes it would have to be prepared in advance but I'll bet there are online or print resources that are not expensive.