To calculate bidding accuracy, Pianola evaluates the contract at your table for each board against the double dummy (or makeable contracts). Double dummy is a theoretical maximum number of tricks that can be achieved by each side for every suit (or NT).
For each board, you will be given one of the following diagnoses:
- Correct bid - meaning there was no bid you could make that would have scored better your way.
- Underbid - there was a higher bid you could have made that would have scored better. This could be either a higher-ranking makeable contract or a profitable sacrifice.
- Overbid - your bid was higher than could be made and would not give you the best possible score if doubled by your opponents.
- Failed to double - your opponents' bid was higher than they could make and you would have scored better if you had doubled them.
- Doubled incorrectly - your opponents' contract was makable, so your double will have increased their score.
Understanding the data
You will find that the bidding accuracy of the top third varies quite dramatically from game to game. It's quite normal to see the winning players bidding as few as a third of the boards "well". In fact, a typical range is anywhere from a third to two-thirds of the boards bid "well". The purpose of this data is to reveal to you whether you and your partner have been more or less successful in finding the optimal contacts.
You might see, for example, that you and your partner consistently underbid more than the top third, meaning your bidding may be too cautious and you're missing out on playing in better-scoring contracts. (That's what the example above would indicate.)
Why does Pianola say I bid badly even though I scored well?
In assessing bidding accuracy, Pianola assumes that both sides will take the number of tricks predicted by the double dummy. Of course this doesn't happen. Good players will take more tricks and weak players will take fewer. However, the purpose of this data is to help you identify if there are any flaws in your general bidding style that you might need to look at. So you will sometimes see examples where Pianola says you overbid, but you actually went on to make the contract and get a good score. However, in this case, it's your skill at playing the cards - or your opponents'' mistakes - that gave you the good score.
Sometimes, Pianola will report that you have under or overbid, but you see that everyone else did the exact same thing. For example, when playing Acol, everyone in the room is likely to find 3NT with a balanced 14 count opposite a balanced 13 count, even though the double dummy may say that only 2NT is actually possible. That's OK. It doesn't mean you should throw your system out of the window. Pianola isn't saying that matching double dummy 100% of the time makes for good bridge; it doesn't. This is why winning players will often only bid, say, half the boards "well".
However, it is important to bid as well or better than your opponents - as long as you make the tricks. There's definitely a correlation between finding good spots (whether as declarer or defender) and then making the most tricks you can.