Match Pointing Two Sections

[Director Paul Lauer asked me to re-publish this article, since he found it informative and it answers questions he has been asked recently. It was originally published on April 7, 2015.]

When there are two or more Sections in an Open game, the scoring software's standard method is to match point each section separately and then to combine the two sections to arrive at an Overall result. Master points are then awarded for doing well in the pair's section as well as Overall. (See Note at end of article.)

Discrepancies can arise when, for a number of possible reasons, a contract and result in one Section is scored with a different match point score than in another Section. So bidding and making 3NT in one Section could be "normal" and result in an average match point, while with the same cards, bidding and making 3NT in the other Section might result in a significantly different match point.

Even in the past, before the advent of dealing machines, each section would play the same cards, because the hands were manually duplicated.  Then and now, people have asked me why these discrepancies are allowed.  They feel pairs are being rewarded or punished due merely to the Section they happened to play in, playing the same cards and getting the same raw score.

Monday's game has some examples. On Boards 5, 6, and 7, the N/S match point scores were as follows:

 Board Section 1 MP  Section 2 MP 
5 (4 making 4) 5.5 4.56
6 (5♣ making 5) 8.5 6.81
7 (4 making 4) 6 5.13

Part of the discrepancy is due to the fact that the Sections were of unequal size. In that case, the software "factors" the match points, so that the percentage remains the same as it would have been had the sizes been the same. But even so, N/S would have scored better in Section 1 than in Section 2 for playing no better. (I have never personally tried to compute a factored result, but I am satisfied that it's correct and fair.)

Of course, the results of individual boards can vary anyway, depending on who you play against, and who else plays your cards against who. It happens all the time, and we live with it because, over time, we'll be a winner in this effect just as often as a loser. The same is true for the "cross section" discrepancies -- you'll be in the "right" Section as often as the "wrong" Section.

The scoring software can be set up to match point across sections, instead. It's slightly more difficult for Diretors, mostly because they have to remember to do it. Before Wednesday's game, I re-scored Monday's game to see what the effects are. The recap is located in the file Monday, 4/6. Test Cross-​Section Matchpointing, Unofficial. I'll try to summarize the effects.

Total number of pairs earning master points: Official: 27, test:25
Highest award: Official: 4.96, test: 4.96
Lowest award: Official: 0.32, test: 0.21
Highest percentage: Official: 68.63, test: 66.22
Lowest percentage earning MPs: Official: 47.35, test: 47.40
Lowest percentage: Official: 33.77, test: 33.21
Total master points awarded N/S: Official: 21.73, test: 20.61

From the above, in this game, 7.4% fewer pairs received MPs, and the total MPs awarded N/S dropped by 5.1%. From the recap, you'll be able to see that some pairs would have done significantly better and some significantly worse. I have no reason to believe these results are typical, and no reason to believe they're not.

From a fairness perspective, it does seem to me that match pointing across sections is more fair, because it reduces the "field balancing" variables by one -- the Section you happen to play in. This only applies to Open games, not to games where there is a 299er Section. We only see such games on Mondays and Fridays in the winter.

Note: Overall results apply to N/S and E/W combined -- this is distinctly unfair and borders on the ridiculous. But that's an issue for another time.

Comments  

# Jim Logan 2015-11-13 11:26
scoring across the field can also be unfair. it is difficult for the director to always balance the field. if you are in a stronger section and every NS makes exactly 4 hearts it is an average board. if in the other section, 3 pairs score 5 hearts due to poor defense, those pairs tie for top. however if the board is scored across the entire field, EVERY NS in the stronger section gets an average minus!!! is that fair????
# Paul Lauer 2015-11-13 11:46
Thank you Pat, I hope your article and any comments
inform club members of scoring difficulties which are
innate in this and many other competitions. The ACBL
score program utilized by most if not all clubs is not
perfect but until something better comes along I believe
it supports an equitable method of evaluating team play.
I am still not committed to across the board scoring but
am open to any & all opinions. Paul

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