Statistical breakdown of practice sessions

[Creeksider]

I practice a lot with GIB and and it occurred to me to wonder how my IMP scores as declarer would compare with scores when defending. I copied results from over 2,000 hands into a spreadsheet and broke them down according to which seat was declarer.

 

My first surprise was to find that I'm declarer 29% of the time, and North 26% of the time. I rarely deviate from GIB's CC and I'm not conscious of bidding more aggressively than GIB. I had assumed the percentages would be about 25% all around but only 45% of the contracts go to opponents.

 

Overall I average about +.82 IMPs for this sample. When North is declarer it's just the brothers GIB playing each other so my positive here (+1.05 IMPs) is purely based on bidding (padded, of course, by many generous gifts from novice players who don't know GIB's system). When I play the cards the average is +1.43, with presumably about the same bidding advantage plus, I like to think, a boost from better declarer play than GIB produces on the faster (i.e weaker) setting).

 

As might be expected, I show better scores when defending against East than when West is declarer: the most important defensive choice is opening lead, and it doesn't require a high level of skill to outperform GIB in that category. On opening lead I'm +.47, but when my partner makes the opening lead my average is a paltry +.11. I'm not sure if this reflects a paucity of opportunities to affect the outcome from this position or a lack of skill (or attention span) on my part when filling this role. If it's the former, I'm spending way too much time thinking about how to play these hands, and if the latter, way too little time.

 

Overall I'm +1.25 when NS play and +.28 when EW play. Perhaps this indicates I need to be bidding a bit more aggressively in some situations but it may simply be the case that skill matters more when you have cards to play.

[Bbradley62]

When North is declarer it's just the brothers GIB playing each other so my positive here (+1.05 IMPs) is purely based on bidding (padded, of course, by many generous gifts from novice players who don't know GIB's system). When I play the cards the average is +1.43, with presumably about the same bidding advantage plus, I like to think, a boost from better declarer play than GIB produces on the faster (i.e weaker) setting).

Why do you seem to be measuring your declarer play against GIB's? Isn't the second component of your score as declarer a result of the difference between your declarer play and that of other Souths?

[Creeksider]

Why do you seem to be measuring your declarer play against GIB's? Isn't the second component of your good score as declarer a result of the difference between your declarer play and that of other Souths?

 

Yes, I misspoke there. When I'm declarer it's me vs. other South declarers (assuming others reach the same contract).

[barmar]

If your statistics are from the MBC rather than tournaments, there's no assurance that humans at the other tables are in the same seat as you.

[Creeksider]

barmar is correct, although if you look at the travelers you see that usually 15 out of the 16 tables had a breather sitting south.

 

After posting I realized aggressive bidding isn't necessarily the reason results are skewed toward declaring as south and to a lesser degree as north. As I get to the end of a session I usually glance at the hand I'm going to leave on the table and If I see a strong one I'll likely decide to play one more because it's a likely opportunity to practice declarer play. I'm not trying to affect the statistics, but this probably happens just enough to produce the anomaly I noted.