jogs, on 2013-September-02, 11:25, said:
Trumps is just one of many variables for estimating tricks.
And Cohen discusses some of them. His books on the LOTT mention adjustments that you should make, such as reducing the number of total tricks when holding lower honors in the opponents' suit. It's also well known that the accuracy of the LOTT goes down significantly at the 5 level and above.
Regarding the hand where North "should double". Sometimes doubled contracts make, that doesn't mean doubling was wrong. There's an old maxim: If you don't give away a few doubled contracts, you're not doubling enough; conversely, if you don't go down in doubled contracts every now and then, you're not bidding enough.