Prajwal bid to a grand slam in clubs after Vinoth (his partner) had shown a balanced hand in the range 22–23 HCP, holding ♠ xxx ♥ xx ♦ Ax ♣ Axxxxx. At the table, the consensus seemed to be that it was an overbid. But was it?
The auction had revealed that all keycards and the ♣ Q were there (which gives Vinoth ♠ A, ♥ A, and ♣ KQ). Vinoth had also denied the ♥ K. Question: Knowing just this much, with no possibility of knowing anything else, is 7 ♣ the right bid for responder?
I ran a simulation with 500 hands (where Vinoth, in addition to the conditions mentioned here, is forced to hold at least 7 controls, which is the average for a 20-point balanced hand). The frequency table for tricks was: 13 - 56.4 %, 12 - 39.8 %, 11 - 3.4 %, 10 - 0.4 %.
You need slightly more than 60 % chances to bid the grand. That suggests that it was an overbid, but close enough. Remembering that this is double-dummy analysis, perhaps one can make the case that, at single-dummy play, it is in fact the right bid?
And just in case you're wondering what happens if Vinoth is the type of guy not to care whether he has 7 controls, the simulation with 6+ controls reduces the chances only slightly.
3 comments:
In addition to the keycards u mentioned, Spade King was also known from bidding.
So please include Spade King in simulation and check whether it increases chances anymore?
If the spade king is included, the table becomes: 13 - 59.2 %, 12 - 36.8 %, 11 - 3.8 %, 10 - 0.2 %. I just discovered that the odds needed to bid grand when the other table is surely bidding at least small is about 55 % at either vulnerability. So with this hand, bidding the grand slam is a slight favourite.
Actually, the 7-controls condition implies the spade king. So the increased figure was just random variation. With 3000 hands: 13 - 57.3 %, 12 - 37.3 %, 11 - 5.1 %, 10 - 0.3 %, 9 - 0.0 %.
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