|How-to use BRidgeBRowser
|Note for those with a "Real" bridgebrowser disk, you can do all of
this on your local data. It is highly recommended that you get the updated
Day 1 can be found here
Day 2 can be found here
Your partnership holds 20 HCP exactly. What is the distibution of tricks made in all Heart contracts (1H to 7H)? How many trumps does it take (on average) to make exactly 10 tricks?
OK, let's do it:
|1. Fire up BRBR Online. The latest version is 2.3A-h-4|
|2. Select S(can R(eset All (only need to do this once, just make sure you havent restricted all your searches on some previous visit)|
|3. Click on the tab about halfway down, BELOW "BRidgeBRowser (tm)" which says "Brd Shape/HCP".|
|4. Press the button marked "clear terms" and, IN ORDER, click on the
LEFT HAND GRID
Click on the square opposite "HCPTeam" under "Dealer"
That display should now look as follows. If it doesnt, press "clear terms" and start this step over again.
|5. Click on the "Contract/Lead" tab. Click the radio button
marked "Specified". You should now get a grid showing all contracts, with
every square corresponding to a possible contract marked green. Clear all
these by clicking the (white) square at top left of that table. Now select
all the Heart contracts by clicking on the word "Hearts". Finally, check
the boz "enable as auxiliary term. The display should look like this:
|6. Click on the tab marked Bid Analysis, check the "Enable as auxiliary term" box.|
|7. Click on the "View" tab, and check the "Enable as auxiliary term" box. Now set the "View from" seat to "Dealer".|
|8. Click on the "Hand Stats" tab, and click the "Enable as auxiliary
term" box. Check the box marked "constrained search" and, IN THE LOWER
TABLE, click on the square under the word "Tricks". The two boxes (one
for IMP, one for MP) will now show "6". Adjust both boxes (left and right)
to say "10". Finally, set the "comparison" radio button to "=". The tab
should now look like this.
|9. Click back to "Brd Shape/HCP" and press "Search". You can watch
the data accumulate on either the Bidding Analysis tab, or the Hand Stats
tab. If you want to see the actual hands and inspect them to make sure
the ones you are pulling out are the right ones, you can go to the "View"
tab and CLEAR the checkbox marked "Suppress main display" (this will have
been checked automatically when you enabled "Hand Stats").
WARNING: this takes a while, unless you have very good access to the server (20 millisecs or less, typical in much of North Eastern US). So you may be happy to restrict this in the Date/Scoring tab - set start and ending data to June 29th 2003 and Sept 28th 2003 (or whatever you like), and press enable as auxiliary term. However you should now go back and restart the search, remembering to START from the Brd Shape/HCP tab. (Should say "SHAPE search" up top of BRBR).
WARNING #2:: It turns out to be OK to stop this particular search prematurely, BECAUSE the primary search key has only one value (20HCP). Normally it is mathematically unsound to stop a SHAPE search as you will have gotten a biased selection of hands, according to which hands' keys came first in the sort order.
When you are done you should have collected (for the dates given above,
not the whole thing) 39933 records.
Look at the Hand Stats tab. It contains the answer to our question:
At IMPS you need an average of 8.77 +/-0.01 hearts to make exactly 10 tricks in a Heart contract. At MPs you need 8.84 +/- 0.01, almost the same.
Is this result surprising? You bet. We can look a bit at the various
screens to see the results in more detail.
|1. Go to the "Bid analysis" tab. If your screen is big enough, stretch
the window downwards by grabbing the bottom, thus:
I carefully moved the "slider" above the table (not visible in the graphic) to "CtrOS" (Contract Opener's Side) so now the statistics relating to contracts are displayed in the 4 columns at the right.
a. You can see from the numbers that we only selected the hands where Hearts was the contract, from the 0 entries in columns CrtOS and CtrNO opposite all other suits and NT.
b. At 2 and 4 levels, there are relatively quite a lot more contracts
played by the opener's side than by the non-opener's side (though we never
said what bid our side had to open with). At 3 and 5 levels the numbers
of CtrOS and CtrNO are almost equal. Perhaps someone could explain this?
|2. Put the mouse on the number "963" (5H-CtrOS) and right-click. Select the first option (All hands). The 5H contracts should now appear in the main screen. Don't press CLEAR or you will have to do the search all over again :) However unchecking and rechecking the "enable" box for "Hand Stats" will result in the analysis for just those hands played in 5H. Notice how bad the scores are for making exactly 10 tricks now, 26.45% and -3.99 IMP.|
|3. Click on the Hand Stats tab, and check "full trick stats".
The trick table will look as follows (scroll over for the MP results):
You may wish to export this lot to Excel using the "Write Report" button I hope you found yesterday.
The law of total tricks is not as simple as you thought. Whilst it may be a winning action to bid for 10 tricks when you have 10 trumps, you can make 10 tricks on half the points in the pack (20) when you have an average of LESS THAN 9 TRUMPS. Presumably with more trumps than that, you make overtricks.
I hope this is useful. Please write to me and tell me what you didn't understand.
Here's the email again
Day 4 may be found at:
|1. Maybe you should go back and try Spades, and the other suits to see if the same patterns are observed.|
|2. You should (always) get the latest client.
that address again:
|3. Now you can go back and ask the same question where the opener and responder both have SPADES. It doesnt matter to look at 2nd/fourth seat having 20 HCP since by the definition of the Milton Work point count, they do already. To do this for 22-18 gets more tricky, as you have to do the whole thing twice to make sure it is the side with 22 that gets to play in the Heart contracts!|