PhilKing, on 2014-September-09, 15:20, said:
I have come back to this now, and redone 24 hands with West always having exactly six diamonds. They are a different set of course, and ducking the diamond comes out way on top. Unbelievably, the contract was now makeable on all 24 hands, but only for sure by ducking the opening lead. If the defence continue diamonds, you can be forced to guess almost all the time. My revised estimate now is that both the spade finesse and endplay/squeeze line are around 40%, and ducking the lead is around 60% - you will play for East to have the king of spades and West to have the diamond guard, and play it as double squeeze. You will probably go off when West has spades and diamonds guarded and East hearts because you will play for East to have been squeezed. So, I must eat humble pie, and what I originally thought was the best line is probably the worst. It was rather better than the line chosen at the table. Of course, we need to multiply that 60% by the chance of West having exactly six diamonds. If that is under 67%, then running some clubs and falling back on the spade finesse is probably right again.