Bridgebrowser Challenge

[cherdano]

How about this one:

Is it right to open in 4th seat with a full opening hand and spade shortness?

 

This has certainly minimal impact on the rest of the system. I am not sure whether the tendency to open such hands is uncorrelated to the strength of players, but I suppose this can be helped by using the rating feature of BridgeBrowser.

 

I suggest to restrict the search to something like 1=4 in the majors and exactly 13 hcp.

 

Arend

[inquiry]

How about this one:

Is it right to open in 4th seat with a full opening hand and spade shortness?

 

This has certainly minimal impact on the rest of the system. I am not sure whether the tendency to open such hands is uncorrelated to the strength of players, but I suppose this can be helped by using the rating feature of BridgeBrowser.

 

I suggest to restrict the search to something like 1=4 in the majors and exactly 13 hcp.

 

Arend

The Fourth seat open/no open is an easy one to program in.

 

For this test, on bid Shape/HCP I assigned first, second, and third seat with 5 to 12 hcp, fourth seat with 12 to 13 hcp and third seat with 0 to 1 spade (upto and including singleton spade Ace). Clearly this will include hands even with 8 or 9 card suits, so further restrictions might should be applied (like no longer than a five card suit or six card suit, and not something like 5-5 or 6-6).

 

On the bidding tab, I made the bidding specify exact seats, and forced first three seats to "pass". Fourth seat could bid anything it wants, including pass.

 

This search turend up 27,202 hands out of 23.5 million in the database I searched that meet all the requirements (passed to the fourth seat, and fouth seat had exactly 12 or 13 hcp and 0 or 1 spade).

 

Of these, 27K hands, 2161 people passed in 4th seat (not enough pearson points). The results for these hands was an average of MINUS 1.15 imps for the hand passing it out (1297 times), and an average of 39.18% matchpoints. This suggest passing an opening hand is the fourth seat IS NOT a winning bid, but may be influenced by shapely hands with other compensating factors (give you something to add to the search and try again).

 

As can be expected, if passing the hands out was BAD, then bidding was good. Opening 1C (+0.07, 50.7), 1D (0.08 and 51.52), and 1H (0.19 and 50.93) were marginally better than "average". 18 brave souls opened 1NT despite the singleton Spade and low point total this worked well at imps and poorly at matchpoints, but too few hands to worry about. Ppening bids of 2C (.98 and 50.44) and 2D (0.09 and 49.44) did well enough but opening 2H was less sucessful (at least at imps) wiht MINUS 0.61 but 52% mp. Most of the three and four level bids turned out very poorly for the fourth seat, the notable exception was 4H opening bid which was +2.16 imps and 55.21% MP, and opening 5C and 5D which both were 3+ imps, and but 5C did poorly at mp (45%) while 5D did well (59%). There were a lot of 4H opening bids but extremely few 5m, especially at matchpoints.

 

But this data, seems to suggest that passing an opening hand in fourth seat is not a good thing. After all, Bridge is a bidders game. Of course, if your partner opens extremely lightly in 2nd seat, that might in general favor an initial pass

 

 

One could subdived the results, easy enough. For instance, for 1♣ opening bids in fourth seat, it is easy to see (using the plot feature) how opening 1♣ with 12 hcp scored versus opening it with 13 (or opening with a singleton versus a void).

 

Turns out, opening on 12 hcp did slighly worse at imps, and slightly better at mp than opeing 1C with 13 hcp. With 1shcp. the imp average was 0.00, the mp average 51.16. While opening with 13 hcp averaged +0.12 but only 50.38%.

 

One might want to speculate as to why opening with minimum hands and short spades works so well in 4th seat (if this data holds up). I think the answer might be that if your RHO passes these days in third seat, he tends to be really broke as third seat light opening bids are all the rage. Thus, of the three other players at the table, the one statistically with most likely fewest hcp in RHO (assuming he will open most 11 hcp and many 9 and 10 hcp with an "excuse").

 

Ben