In this series, we are analyzing 1,000,000 deals which were played on-line. These deals cover a wide range of level of play and were provided by Stephen Pickett with Bridge Browser.
When the final contract was 1NT, it was set about 29% of the time and made 71% of the time (often with overtricks).
Here is how many tricks were taken (in order of frequency):
7 -- on 25% of all 1NT contracts
8 -- on 23% of all 1NT contracts
6 -- on 17% of all 1NT contracts
9 -- on 15% of all 1NT contracts
5 -- on 8% of all 1NT contracts
10--on 6% of all 1NT contracts
When the 1NT bid was a direct overcall (passed out in 1NT), the overcaller averaged 45% at matchpoints and went slightly minus in IMP expectancy.
In contrast, when the auction went 1NT-Pass-Pass-Pass, this was very good for opener's side. At matchpoints it resulted in an average of 58% and at IMPs a gain of nearly 1/2 imp per board. These are remarkably high averages. It proves what I've always known: "If at all possible, interfere over the opponents' 1NT opening, especially in balancing seat."
Next month: On what percent of deals is the contact played by the same side who opened the bidding?