Scoring

[hotShot]

At IMPs you get nothing for 10 point difference.

At XIMPs your score is compared with several other scores and averaged over these. The 10 points more you have over some, can make 1 IMP more difference compared with others. So you will see that a 10 point difference can give you a faction of an IMP more at XIMPs than those who have 10 points less. Of cause not always, but sometimes.

[shyams]

At IMPs you get nothing for 10 point difference.

At XIMPs your score is compared with several other scores and averaged over these. The 10 points more you have over some, can make 1 IMP more difference compared with others. So you will see that a 10 point difference can give you a faction of an IMP more at XIMPs than those who have 10 points less. Of cause not always, but sometimes.

I think the fractions happen due to other results and not caused by the 10 pt differences.

Suppose we had a deal where 4♠ makes 4 and 3NT also makes 4. Say 6 out of 16 tables play 4♠ and the remaining play in 3NT. If all tables make 10 tricks, the cross-IMP score is ZERO for all tables.

[helene_t]

True, HotShot, but you have to see it this way:

 

Suppose you get 420 and the competition is 50% likely to get 400 and 50% likely get get 430. This means that you have a 50% chance of winning 1 IMP, iow your average win is 0.5 IMP.

 

At XIMPs, in a large field, you will actually get something close to 0.5.

 

At teams (which is another word for XIMPs with only two tables), you will either win 0 or 1 IMP. Your expectation is 0.5 IMP.

 

You should base your decisions on expectation so the XIMP strategy is identical to the teams strategy.

[hotShot]

Seems we are very close in our perception. Perhaps you would agree that an overtrick counts more:

MP>>XIMPs>IMPs.

[helene_t]

No, an overtrick counts exactly the same. On average, it is. Of course it could count a fraction in XIMPs and it won't count a fraction in teams. So in teams the fluctuations are bigger. More generally, the bigger the field the smaller the fluctuations.

 

Your XIMP score is like an average of a lot of team matches, each being played against a different table. So the expectation is the same. The variance is different.

[hotShot]

Well the tourney ranks depend on the fractions, especially midfield.

Taking a small extra risk can make a difference.

Lets say they variance is a factor there.

[helene_t]

Lets say they variance is a factor there.

I suppose it could be. Depends what your objective is.

 

I was assuming that your objective is to maximize your long-term IMP average. It appears to make very little difference in a teams tournament whether you maximize VP or IMPs.

 

You may have a preference for high variance (if you are underdog or if you need to improve your score) or for low variance (if you are overdog or you need to preserve your score).

[pirate22]

ty all for inputs---when i originally submitted my query,

the bidding went ply sayc 5cm and 1 d=min 4 cards.....

 

1cl--1sp

2sp--3d my pard shld have now 5 sp and a diamond suit(4) may have a factor,and as i had a heartfactor with diam support-i was also protecting my Kx factor in clubs--and elected to bid 3n/t (knowing we shld have a 5x4 spade fit.not always the case---so many players if they respond 1d over 1cl the 1cl assumes wrongly that the 1 d bidder has no 4 card major.this i hAVE FOUND OUT TO MY COST. SO THEYBID the spade first,and then bid diamonds,

 

as it happened my pard had 5 spades and 4 diamonds,and either contract was safe

regards

[babalu1997]

ty all for inputs---when i originally submitted my query,

the bidding went ply sayc 5cm and 1 d=min 4 cards.....

 

1cl--1sp

2sp--3d my pard shld have now 5 sp and a diamond suit(4) may have a factor,and as i had a heartfactor with diam support-i was also protecting my Kx factor in clubs--and elected to bid 3n/t (knowing we shld have a 5x4 spade fit.not always the case---so many players if they respond 1d over 1cl the 1cl assumes wrongly that the 1 d bidder has no 4 card major.this i hAVE FOUND OUT TO MY COST. SO THEYBID the spade first,and then bid diamonds,

 

as it happened my pard had 5 spades and 4 diamonds,and either contract was safe

regards

maybe you can have a look at the walsh diamond convention, and perhaps move this to another thread.

 

http://www.bridgehands.com/W/Walsh_Diamond_Responses.htm