CardShark BidBase
Bidding Practice

Conventions Available:


CardShark BidBase is a series of bridge related programs built around a database in which the hand specifications for each bid is stored in a database, thus allowing any bidding convention or other bids to be recorded.

The main program in the series is the BidBase Practice Program which itself has numerous features, one of which is the ability for users to practice drills for bidding conventions.

Because BidBase is not yet ready for distribution, the drills have been exported into Web page format so that they can be used in any device with a Web browser.

Each of these convention practice pages contains 100 hands with the bidding and a sequence number 1-100, and the BidBase deal number.

After you decide on a bid, click on Next bid to see what BidBase bids. You do not have to enter the bid you decide on.

On some quizzes, after you click to see what BidBase thinks you should have made, you will also be shown opener's response to that bid. Then you can decide on your next bid and click to see that bid as well.

You will also be shown opener's hand and the Double Dummy Analysis ("DDA") for the hand, showing how many tricks you could take on each strain (club through notrumps); however, BidBase does not use DDA in arriving at a bid. Its bidding is based on the hand specifications for each bid in the BidBase database.

Because DDA can see all the hands, it counts all possible winners, such as a finesse which wins, but it would not count the same finesse by N-S with the E-W hands swapped. Consequently, it may say that a game or slam is makeable given the specific lay of the cards it sees, but bidding the game/slam could be a losing proposition in the long run.

So if BidBase does not bid a game or slam which DDA says will make, it could be because of a flaw in BidBase which should be pointed out and fixed, or it could be that BidBase's bidding is theoretically correct but doesn't happen to work out for the current deal.

Please point out any bidding which you consider to be flawed so that we can fix it.

Each practice page contains a link to a Web page with a description of the convention and the hand requirements for each bid.

The bidding in these quizzes is all done by the BidBase Practice Program.

If you disagree with BidBase's bid, email the deal number and your comments to --
Before emailing, please read the convention's Web page to see the bidding criteria used.

All the quizzes have been reviewed and in the course of doing that, some comments have been added if the convention's web page does not adequately explain the bidding or BidBase's bidding criteria may not be commonly used.

To clear the answers on a quiz page, reload or refresh the page.

When you are ready to stop, make a note of the number of the last deal you try if you don't want to start over next time.

Because answers may change as the database continues to be updated, each page shows the page it was last updated. When we re-do the pages, we will start with a higher deal number in order to vary the quizzes.

Deal Numbers:

The deal numbers are included in order to make it easier to look up the source of a quiz hand if there is a problem with it.

The deal number can also give you an idea of how many random deals it took to come up with 100 deals matching the conventions starting auction.

Each deal is checked for a matching convention auction using each position as dealer. So if the deal number for the last practice hand is, say, 5000, BB has actually tried the equivalent of 5000 x 4, or 20,000 deals to get 100 matching deals for the convention, or 1 in 200.

So the odds of your getting to bid that convention in a 27-board event are 1 in 200 / 27, or one deal in every 7.4 events. The odds of a pair - you or partner - bidding the convention would be twice that (2 in 200), or once in every 3.7 events.

Either way, that's a long time between uses of the convention which is why it is a good idea to practice the conventions now and then to keep them fresh in your memory. 


The DDA (Double Dummy Analyzer) numbers after each BidBase bid come from the same DDA routine (written by Bo Haglund) that's on the Village Card Club web site.

Because the quizzes are taken from full random deals which BidBase generates, it can see all the hands and apply the DDA to them; however, BidBase does not use DDA in its bidding. It used bid specifications stored in its database.

Comparing BidBase's bids to what DDA shows can be very interesting. DDA results are not always reflect technically correct play, but they do show what is possible.

For standard computer spacing purposes, BidBase uses 1 letter for call strains:
      N = NT
      D = Dbl
      R = Redbl
      P = Pass