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Hand Evaluation

#41 User is online   PeterAlan 

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Posted 2012-February-09, 19:16

View PostVampyr, on 2012-February-09, 18:58, said:

Why does this matter if it meets other desirable criteria, chiefly that the player are used to it and like it?

Because those are probably not informed views (can we accept that this is not a patronising statmenet? - see discussion above). What I'm suggesting is that there should be an honest acceptance of the shortcomings; until that's forthcoming, statements like this are, to mix my metaphors, just sweeping the issue under the carpet and hiding behind skirts.
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#42 User is offline   Vampyr 

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Posted 2012-February-09, 20:56

View PostPeterAlan, on 2012-February-09, 19:16, said:

Because those are probably not informed views


Informed of what?
I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones -- Albert Einstein
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#43 User is offline   Trinidad 

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Posted 2012-February-10, 00:36

View PostVampyr, on 2012-February-09, 18:58, said:

Why does this matter if it meets other desirable criteria, chiefly that the players are used to it and like it?

The point is that this discussion got started because one of the players clearly did not like it.

In addition, there is the fact that people have already been thinking of a solution. After all, there must have been a reason why people were polled with the question whether they wanted the format changed from team of 8 to 2 teams of 4. I obviously don't have any hard evidence, since I was far from involved, but it seems to indicate that there must have been some kind of problem with the scoring. In general, people do not try to look for solutions if there isn't a problem.

View PostVampyr, on 2012-February-09, 20:56, said:

View PostPeterAlan, on 2012-February-09, 19:16, said:

Because those are probably not informed views

Informed of what?

Uninformed about the issues that f0rdy mentioned in post #13 and uninformed about the fact that there is a very simple way to correct these issues.

It may well be that the field of players is divided into two parts:
1) The happy oblivious: The part that is completely unaware of the oddities of the use of the team of four IMP scale in team of eight events.
2) The uneasy aware: The part that realizes that there is something odd with the IMP scale in team of 8 events, dislikes it, but accepts it since they can't really see what causes this oddity and since they are unaware of the solution.

It might well be that in the future there will be a growing third:
3) The annoyed enlightened: The part that knows what causes the scoring oddities in team of eight events and knows that there is a simple solution, but is unhappy with the fact that this solution is not used.

The easiest way to introduce innovations and get them accepted is to implement them at the point when the third group is large. The best way to introduce innovations is as early as possible (once the innovation has been developed) while making sure that the third group grows rapidly to facilitate the acceptance of the innovation.

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
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#44 User is online   PeterAlan 

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Posted 2012-February-10, 03:21

View PostVampyr, on 2012-February-09, 20:56, said:

Informed of what?

As I said, see discussion above. This was an excellent summary, if you don't want to scroll back.

View PostTrinidad, on 2012-February-09, 08:29, said:

F0rdy and campboy clearly showed that, by applying the team of four IMP table to teams of 8, you are changing the IMP scale. They showed that the scoring gets "warped" when you use the team of four IMP scale for team of eight games. The team of four IMP table was never meant for teams of eight. (Just think what this would do if someone would organize a "team of 400" match ...)

My post was showing that it is very easy to adapt the existing IMP scale for teams of 6, 8, 10 or 400, in such a way that this "warp" is compensated for. This doesn't make it a different IMP scale. It is the exact same IMP scale, but now for another number of participants on the team.
...
Mathematicians, statisticians and engineers know these kind of methods as "scaling". ... I can see that scaling in such an abstract thing as bridge scoring may appear confusing, but it is simply a question of doing things right.

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#45 User is offline   gordontd 

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Posted 2012-February-10, 03:47

When I've run a heat for a national teams-of-eight competition which is scored by adding all four scores together, I've provided the players with the appropriate IMP scale. Most of them don't notice. None of them (including Stefanie) have ever said they would prefer to have the unsuitable team-of-four scale.
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#46 User is offline   Trinidad 

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Posted 2012-February-10, 03:58

View Postgordontd, on 2012-February-10, 03:47, said:

When I've run a heat for a national teams-of-eight competition which is scored by adding all four scores together, I've provided the players with the appropriate IMP scale. Most of them don't notice. None of them (including Stefanie) have ever said they would prefer to have the unsuitable team-of-four scale.

Darned, I was soooo hoping that in the future I would see tournament announcements with a phrase like: "Form of scoring: Teams of 8, according to the (well-known, famous, brilliant, ...) Trinidad scale".

This means that I will have to work harder on earning the Nobel Prize to achieve immortality.

;)

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
The only reason God did not put "Thou shalt mind thine own business" in the Ten Commandments was that He thought that it was too obvious to need stating. - Kenberg
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#47 User is offline   f0rdy 

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Posted 2012-February-10, 04:39

View Postbarmar, on 2012-February-09, 14:17, said:

Scoring a game is essentially arbitrary, it can be done any way the game designers want.

However, if they declare a specific set of goals for the scoring system, you can determine whether the scoring system achieves those goals. That could be a "logic" of scoring.

For instance, when the rules for doubled undertricks was changed, it was because players and administrators felt that the old rules made it too easy to sacrifice. That feeling was a popularity issue, but the scoring changes were a logical consequence.


Of course. There are at least 3 (?) common methods of getting from raw scores (420, 1430, etc) to comparisons for duplicate, and everyone knows that they require different approaches to aspects of bidding and play. My concern about the "teams-of-eight with standard IMP table" is that I think most people sit down and assume they're playing "IMPs", ie ordinary teams of four scoring, and that they should bid and play accordingly; this isn't entirely true, particularly with regard to large scores from slams or bad sacrifices.

I suspect that nearly everyone playing in this competition for Cambridge UBC falls into either the "happily oblivious" or the "enlightened" (probably with varying degrees of annoyance). The question of course, is which of Trinidad's categories members of the other 7 counties fall into, and whether the "happily oblivious" would be resistant to change; I agree entirely with Bluejak that these events should be run with whatever keeps the players happy, within bounds of fairness (which I agree this doesn't affect).

Peter

PS Yes, this is analogous to the "how to score IMP pairs" question, but I think this is less bad than IMPing against a datum, which is completely barmy; I actively avoid playing in Butler-scored events unless required to.
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#48 User is offline   gwnn 

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Posted 2012-February-10, 04:47

View Postbarmar, on 2012-February-09, 10:39, said:

Who gets to dictate what's logical?

Logic?
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#49 User is offline   StevenG 

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Posted 2012-February-10, 04:51

View Postf0rdy, on 2012-February-10, 04:39, said:

The question of course, is which of Trinidad's categories members of the other 7 counties fall into, and whether the "happily oblivious" would be resistant to change


"Happily oblivious" to a man, I'd suggest - certainly at B & C team level. The IMPs scale is just a lookup table; I can't imagine anyone caring if it was changed slightly.
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#50 User is offline   gwnn 

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Posted 2012-February-10, 04:53

BTW why would people be so resistant to a change in IMP scale (w.r.t. number of people on a team) when they are completely fine with a changing VP scale (w.r.t. number of boards)?
... and I can prove it with my usual, flawless logic.
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#51 User is offline   Trinidad 

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Posted 2012-February-10, 05:29

View Postgwnn, on 2012-February-10, 04:53, said:

BTW why would people be so resistant to a change in IMP scale (w.r.t. number of people on a team) when they are completely fine with a changing VP scale (w.r.t. number of boards)?

Beats me. I thought this was extremely simple. (I can understand that people find it difficult to understand how the IMP scale should be changed to make it like teams of four, but that is what mathematicians and engineers are for.)

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
The only reason God did not put "Thou shalt mind thine own business" in the Ten Commandments was that He thought that it was too obvious to need stating. - Kenberg
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#52 User is offline   gnasher 

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Posted 2012-February-10, 06:55

View Postf0rdy, on 2012-February-10, 04:39, said:

I suspect that nearly everyone playing in this competition for Cambridge UBC falls into either the "happily oblivious" or the "enlightened" (probably with varying degrees of annoyance).

Aren't they all too clever to fall into the "happily oblivious" camp?
... that would still not be conclusive proof, before someone wants to explain that to me as well as if I was a 5 year-old. - gwnn
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#53 User is offline   campboy 

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Posted 2012-February-10, 07:30

View Postgnasher, on 2012-February-10, 06:55, said:

Aren't they all too clever to fall into the "happily oblivious" camp?

That just affects the conclusion they come to once they stop to consider the merits of the scoring system, and some won't have done that. After all, most of the cantankerous people spend more time talking about cross-imps vs butlers or how the home team should move.
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#54 User is offline   bluejak 

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Posted 2012-February-11, 17:00

View PostTrinidad, on 2012-February-10, 00:36, said:

The point is that this discussion got started because one of the players clearly did not like it.

In addition, there is the fact that people have already been thinking of a solution. After all, there must have been a reason why people were polled with the question whether they wanted the format changed from team of 8 to 2 teams of 4. I obviously don't have any hard evidence, since I was far from involved, but it seems to indicate that there must have been some kind of problem with the scoring. In general, people do not try to look for solutions if there isn't a problem.

I think this is a very unfair presumption. The reason that I polled them is that I realised that two teams-of-four would make the game what some people seem to call 'logical', ie more in line with playing teams-of-four, and because the scoring of the event [which was done by hand in those days] would be far simpler. Since I was the organiser [at the time] and the TD, it did not matter one brass farthing to me personally which way they decided really, and I would not let it affect me if it did.

Since no-one polled wanted a change I fail to see how you can presume the poll was because someone did.

View Postf0rdy, on 2012-February-10, 04:39, said:

PS Yes, this is analogous to the "how to score IMP pairs" question, but I think this is less bad than IMPing against a datum, which is completely barmy; I actively avoid playing in Butler-scored events unless required to.

Now I think that Butler has a lot to recommend it. At lower levels especially I think it is a better scoring method. Why? Because I think it better for the customers being more comprehensible to poor players.

View Postgwnn, on 2012-February-10, 04:53, said:

BTW why would people be so resistant to a change in IMP scale (w.r.t. number of people on a team) when they are completely fine with a changing VP scale (w.r.t. number of boards)?

There are lots of different VP scales so no-one thinks of any one scale as the VP scale. but there is only one imp scale.
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#55 User is offline   Trinidad 

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Posted 2012-February-11, 19:08

View Postbluejak, on 2012-February-11, 17:00, said:

I think this is a very unfair presumption. The reason that I polled them is that I realised that two teams-of-four would make the game what some people seem to call 'logical', ie more in line with playing teams-of-four, and because the scoring of the event [which was done by hand in those days] would be far simpler. Since I was the organiser [at the time] and the TD, it did not matter one brass farthing to me personally which way they decided really, and I would not let it affect me if it did.

Since no-one polled wanted a change I fail to see how you can presume the poll was because someone did.

There is nothing unfair about my presumption. For starters, I was very clear that this was merely an indication.

If you "realised" that two teams of four would make the game more logical, you missed an important point of this discussion: It is complicated to come up with a single result when you split it in two teams of four matches. After all, you can match up:
- Table 1 and 2 in match 1 and table 3 and 4 in match 2
- Table 1 and 3 in match 1 and table 2 and 4 in match 2
- Table 1 and 4 in match 1 and table 2 and 3 in match 2

Each of these match-ups will lead to different results.

So there are two things you can do:
- Split up the team of 8 into two teams of 4 people. The consequence is that people won't play in a team of 8 anymore, but in a team of 4 whose result depends on that of another team of 4. That is principally different from team of 8.
- Calculate the results for the three different match-ups separately and add (or average) them. Now you have true teams of 8, with each pair in a team depending equally on each other pair. The only thing is that this is a lot harder to calculate than the method that uses an adjusted IMP scale.

And, as I explained earlier, it is pretty obvious that no one wanted to change if the only change that they can chose for is changing things for the worse.

View Postbluejak, on 2012-February-11, 17:00, said:

Now I think that Butler has a lot to recommend it. At lower levels especially I think it is a better scoring method. Why? Because I think it better for the customers being more comprehensible to poor players.

Can you tell me why "first averaging results and then IMP" (Butler) is easier to comprehend than "first IMPing and than average results" (Cross-IMPs)? I would think the second is much easier to explain, since it is the correct order of doing things in every aspect of life: you average at the end, not at the beginning.

I think it is very hard to explain to poor players (and to good players) why the EW pairs on board 1 on average got an IMP more than the NS players (just to name only one oddity of Butler). What do you say when they come to you and tell that there must be a scoring error?

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
The only reason God did not put "Thou shalt mind thine own business" in the Ten Commandments was that He thought that it was too obvious to need stating. - Kenberg
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#56 User is offline   Trinidad 

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Posted 2012-February-11, 19:20

View Postbluejak, on 2012-February-11, 17:00, said:

There are lots of different VP scales so no-one thinks of any one scale as the VP scale. but there is only one imp scale.

It is true: There is only one IMP scale. So why don't you use that one, instead of the "warped" one you are using?

I know, you don't realise that you are using a warped IMP scale, because you are fixed on numbers, rather than on underlying principles. I will try to explain. It is late at night here, which means that I am getting somewhat theatrical. I apologize, but please bear with me. At the end of the theater you may understand.

You know that there is only one IMP scale. But did you know that there is also only one VP scale. (?!?) Yes, indeed, there is only one VP scale.
I don't know what it is, but this VP scale always "bends" at the exact right places, whether you play 8 or 32 boards. I know, the numbers are different, but the bending of the scale is always at the same place: Whether you win 16-14 in VP at the end of 8 boards or after 32 boards, in both cases you will feel that it could have gone either way. And if you win 20-10, you feel that you had a solid win. Whenever you win 25-3, you felt that you were blitzing them. The VP scale expresses achievements in numbers. And it does so always in the same way. 4, 8, 12, 24 or 32 boards: it doesn't matter. The VP scale always shows how much stronger (or weaker) you were than the opponents. It is mystical, no, no, ...magical.. how this can be achieved.

If you compare the VP table for 8 boards to the VP table for 32 boards, you will notice something interesting: The IMP differences of the 8 board table are half of the IMP differences of the 32 board table. What a coincidence! Or might it be deliberate? 8/32=1/4, and the square root of 1/4 equals 1/2! That is too much of a coincidence.
Wait a minute! There is only one VP scale! All VP scales are mathematically created from one universal, invisible Master VP scale. Now where did I hear that concept before?

Losely adapted, Genesis 1:26 said:

'And the Master VP scale said: "Let us make VP scales in our image, in our likeness, so that they may rule over the palookas in the clubs and the pros in the tournaments, over the rabbits and the hogs, and over all the players that move for the round."'

I believe that the one IMP scale is just as Almighty as the one VP scale.

Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
The only reason God did not put "Thou shalt mind thine own business" in the Ten Commandments was that He thought that it was too obvious to need stating. - Kenberg
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#57 User is offline   bluejak 

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Posted 2012-February-12, 17:42

View PostTrinidad, on 2012-February-11, 19:08, said:

There is nothing unfair about my presumption. For starters, I was very clear that this was merely an indication.

If you "realised" that two teams of four would make the game more logical, you missed an important point of this discussion: It is complicated to come up with a single result when you split it in two teams of four matches. After all, you can match up:
- Table 1 and 2 in match 1 and table 3 and 4 in match 2
- Table 1 and 3 in match 1 and table 2 and 4 in match 2
- Table 1 and 4 in match 1 and table 2 and 3 in match 2

Each of these match-ups will lead to different results.

So there are two things you can do:
- Split up the team of 8 into two teams of 4 people. The consequence is that people won't play in a team of 8 anymore, but in a team of 4 whose result depends on that of another team of 4. That is principally different from team of 8.
- Calculate the results for the three different match-ups separately and add (or average) them. Now you have true teams of 8, with each pair in a team depending equally on each other pair. The only thing is that this is a lot harder to calculate than the method that uses an adjusted IMP scale.

And, as I explained earlier, it is pretty obvious that no one wanted to change if the only change that they can chose for is changing things for the worse.

Your presumptions are getting more and more extreme and teetering on the edge of being rather rude. Of course there are several ways you can do it. When I polled them I gave them an easy working alternative: I did not just tell them a load of confusing rubbish. They just preferred the present method. Why is that so hard to understand?

View PostTrinidad, on 2012-February-11, 19:08, said:

Can you tell me why "first averaging results and then IMP" (Butler) is easier to comprehend than "first IMPing and than average results" (Cross-IMPs)? I would think the second is much easier to explain, since it is the correct order of doing things in every aspect of life: you average at the end, not at the beginning.

The concept of a datum is one people find easy to understand. Cross-imps has no datum. Easy peasy.

View PostTrinidad, on 2012-February-11, 19:08, said:

I think it is very hard to explain to poor players (and to good players) why the EW pairs on board 1 on average got an IMP more than the NS players (just to name only one oddity of Butler). What do you say when they come to you and tell that there must be a scoring error?

Poor players do not worry about the oddity of Butler once they understand the principle, you get a datum, you imp against that.

View PostTrinidad, on 2012-February-11, 19:20, said:

It is true: There is only one IMP scale. So why don't you use that one, instead of the "warped" one you are using?

I know, you don't realise that you are using a warped IMP scale, because you are fixed on numbers, rather than on underlying principles. I will try to explain. It is late at night here, which means that I am getting somewhat theatrical. I apologize, but please bear with me. At the end of the theater you may understand.

You know that there is only one IMP scale. But did you know that there is also only one VP scale. (?!?) Yes, indeed, there is only one VP scale.
I don't know what it is, but this VP scale always "bends" at the exact right places, whether you play 8 or 32 boards. I know, the numbers are different, but the bending of the scale is always at the same place: Whether you win 16-14 in VP at the end of 8 boards or after 32 boards, in both cases you will feel that it could have gone either way. And if you win 20-10, you feel that you had a solid win. Whenever you win 25-3, you felt that you were blitzing them. The VP scale expresses achievements in numbers. And it does so always in the same way. 4, 8, 12, 24 or 32 boards: it doesn't matter. The VP scale always shows how much stronger (or weaker) you were than the opponents. It is mystical, no, no, ...magical.. how this can be achieved.

If you compare the VP table for 8 boards to the VP table for 32 boards, you will notice something interesting: The IMP differences of the 8 board table are half of the IMP differences of the 32 board table. What a coincidence! Or might it be deliberate? 8/32=1/4, and the square root of 1/4 equals 1/2! That is too much of a coincidence.
Wait a minute! There is only one VP scale! All VP scales are mathematically created from one universal, invisible Master VP scale. Now where did I hear that concept before?


I believe that the one IMP scale is just as Almighty as the one VP scale.

Now you are talking complete rubbish. Of course there is not only one VP scale. Please explain how my 17-3 win in Swiss Pairs is identical to my 8-4 win in my local league. And don't think that your method of blinding me with numbers proves anything: it doesn't.

I do think one of the problems is that you do not realise that simple concepts can be explained simply.
David Stevenson

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Visiting IBLF from time to time
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#58 User is offline   gordontd 

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Posted 2012-February-13, 02:53

View Postbluejak, on 2012-February-12, 17:42, said:

Poor players do not worry about the oddity of Butler once they understand the principle, you get a datum, you imp against that.

Sure they wonder: why do we discard some scores, how many scores are discarded? And then less inexperienced players might wonder how it is determined the number of scores that are discarded, why they can't find a regulation to explain this, what happens to scores that fall between the IMP scales, and why an improved score on one board might make their overall score worse.

By contrast, I have never known players have difficulty understanding Cross-IMPs when it is explained properly to them.
Gordon Rainsford
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#59 User is offline   WellSpyder 

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Posted 2012-February-13, 03:31

FWIW, I feel strongly that Cross-imps are better than Butler imps, and suggest changing from Butlers whenever the opportunity arises. But there is usually very little enthusiasm for this since everyone is used to Butlers and most don't care about the distortions involved.

As far as the main topic of conversation here is concerned, I play in two different teams of 8 leagues. The Midlands inter-county league, unlike the Eastern counties one that started this discussion, is scored as 2 teams of 4. It still feels very much like a teams of 8 match, though, since you end up playing all 4 pairs in the opposing team, and of course the scores of both teams of 4 are added together at the end. Within our county, on the other hand, we run a large teams of 8 league (around 40 teams in 5 divisions) which is scored by adding all 4 scores together and imping using the standard teams of 4 scale. (I also tend to play once a year in a multiple teams of 8 inter-county event that is scored by imping with both pairs sitting the other way. This uses the standard teams of 4 imp scale, but needs a special VP scale since there are 4 imps scores on every board.)

Having experience of all these, I think the cross-imp form of teams of 8 is probably the purest way to score. But I much prefer actually playing in the league that simply scores as 2 teams of 4, because it is so simple! The players can very quickly score up as normal and know how well they have done, whereas both the other forms of scoring take significantly longer, and are probably quicker to do on a computer than by hand.
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#60 User is offline   mjj29 

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Posted 2012-February-13, 03:44

View Postbluejak, on 2012-February-12, 17:42, said:

The concept of a datum is one people find easy to understand. Cross-imps has no datum. Easy peasy.

Really? I don't understand the concept of a datum - I have no idea why you would consider the mean of the available scores a reasonable thing to imp against or why it's reasonable to discard that number of outliers. I don't understand why it's ever reasonable to imp against a score that noone (including the computer) actually got on that board.

Cross-imps, on the other hand, are both very easy to explain to people ('you imp against everyone and take the average') and seem much more sensible when you consider them in any detail.

View Postbluejak, on 2012-February-12, 17:42, said:

Poor players do not worry about the oddity of Butler once they understand the principle, you get a datum, you imp against that.


Surely poor players don't worry about the scoring at all though and would be happy with any method of scoring. At best they want to know 'is it IMPs or pairs', although most of them don't change their play either way, it just gives them a different set of excuses for bidding failing games. Why, therefore, should we give them a statistically bogus method of scoring, rather than a reasonable one?
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