[BLML] implementing 12C1c (weighted adjustments)

Herman De Wael hermandw at skynet.be
Thu Mar 3 09:08:13 CET 2016



Timothy N. Hill schreef:
> The ACBL changed its method of assigning adjusted scores, effective
> January 1, from 12C1e (most favorable/unfavorable) to 12C1c
> (probability-weighted). We don’t yet have any software support for
> 12C1c adjustments.
>

congratulations!

> I have a few questions for old hands with 12C1c.
>
> Consider this example: A pair stops in game after receiving
> misinformation and scores 680, but we estimate they had a 50% chance
> of bidding slam if correctly informed. The other scores are -100,
> 650, 680, 710, 1430, and 1460.
>
> The ACBL suggests we slightly favor the non-offending side in
> assigning weights. Is this the practice elsewhere?
>
> Say we weight 680 at 40% and 1430 at 60%. Manually calculating the
> adjusted matchpoints is easy enough: 40% x 2.5 + 60% x 4.5 = 3.7.
>
> How should the other scores be matchpointed?
>
> I think the other scores should also be weighted:
>
> -100                           0 650                           1 680
> 40% x 2.5 + 60% x 2   = 2.2 710   40% x 4   + 60% x 3   = 3.4 40%
> 680, 60% 1430   40% x 2.5 + 60% x 4.5 = 3.7 1430   40% x 5   + 60% x
> 4.5 = 4.7 1460                           6
>
> Is this the preferred method elsewhere?
>

It is (equivalent to) my preferred method. But I know of no regulation 
that adopts this approach, nor of any program that supports it.

> Unfortunately, the current ACBLscore won’t do this calculation. For a
> small top, we could matchpoint the whole board manually, but that’s
> impractical for a large top.
>
> If we enter the adjusted score as 3.7 matchpoints, the current
> ACBLscore will Neuberg the other results:
>
> -100               0 +  1/12 = 0.08 650               1 +  3/12 =
> 1.25 680               2 +  5/12 = 2.42 710               3 +  7/12 =
> 3.58 40% 680, 60% 1430   40% x 2.5 + 60% x 4.5 = 3.7 1430
> 4 +  9/12 = 4.75 1460               5 + 11/12 = 5.92
>
> How do other scoring programs support 12C1c adjustments?
>

Similarly.

> Is there a syntax for entering “40% of the matchpoints for 680 plus
> 60% of the matchpoints for 1430”?
>

Only the "Maastricht method" that David Stevenson and myself developed 
in 2000, and which states that the scores be listed in descending order 
of NS value, with percentages or fractions, and with a plus between all 
(I mean the word plus).

Herman.

> Thanks!
>
> Tim _______________________________________________ Blml mailing
> list Blml at rtflb.org http://lists.rtflb.org/mailman/listinfo/blml
>


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