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Looking for exact IMP pairs calc IMP Pairs Calculation

#1 User is offline   James_H 

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Posted 2020-June-29, 12:03

I'm looking for the exact BBO calculates IMPS

Here is an sample
Table	Contract	Score	IMPs
1	6♦N=	        920	11
2	6♣xE-3	        500	1.67
3	4♠S+2	        480	0.83
4	5♠N+1	        480	0.83
5	5♦N+1	        420	-0.83
6	5♦N+1	        420	-0.83
7	4NS-5	       -250	-12.67


I notice that it has the neat property that the IMPS sum to zero which does not always happen with cross imps.
Wondering how the calculation comes up with partial IMPS

Thanks, James.
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#2 User is offline   Stephen Tu 

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Posted 2020-June-29, 12:22

View PostJames_H, on 2020-June-29, 12:03, said:

I'm looking for the exact BBO calculates IMPS

I notice that it has the neat property that the IMPS sum to zero which does not always happen with cross imps.Wondering how the calculation comes up with partial IMPS


It's just cross-imps. For each table's score, IMP compare vs every other score. Add to get total. Divide by number of comparisons to get an average.


The IMPS should sum to zero when done this way. (As opposed to "Butler", the antiquated way of doing IMP pair scoring based on IMP comparing vs the "datum", average of bridge raw scores sometimes with dropping of extremes. Butler was only necessary with scoring without computer help, there's no good reason to use it anymore IMO).
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#3 User is offline   James_H 

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Posted 2020-June-29, 12:33

View PostStephen Tu, on 2020-June-29, 12:22, said:

It's just cross-imps. For each table's score, IMP compare vs every other score. Add to get total. Divide by number of comparisons to get an average.


The IMPS should sum to zero when done this way. (As opposed to "Butler", the antiquated way of doing IMP pair scoring based on IMP comparing vs the "datum", average of bridge raw scores sometimes with dropping of extremes. Butler was only necessary with scoring without computer help, there's no good reason to use it any more IMO).


Thank you Stephen.
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