In the last section we talked about the difference in scoring between IMPs and Match Points. This time we’ll see how it applies to the decision about whether or not to double them when they bid over us in a part-score battle.
At MPs there’s a big incentive to double. If you are making 110 or 140 in 3♣ or 3♥, and they bid 3♦ or 3♠ over that, and are set 1 trick vulnerable for 100 or 2 tricks not vulnerable for the same measley 100, you will get a very bad score.
Remember, at MPs it is a matter of how many scores you beat, not by how much, so that 10 or 40 points can be very important.
Let’s look at an 8-table game where both sides are vulnerable and both sides can make 8 tricks, one in hearts and one in spades.
Note that these scores are for the NS pair, the scores for the EW pair would be inverted, with 0 being the best one here and 7 the worst. On OKBridge, both sides will have their scores reflected in percentages with the best for their direction being 100% (unless it is shared) and the worst 0%.
Notice that the only pair that did nearly as badly as the one who was doubled in 3♠ was the one who let the opponents play quietly in 2♥.
Now, let’s change things a bit and suppose that while NS can only make 8 tricks, EW can make 9.
Once EW compete to 3♥, the NS pair can score a maximum of 3 match points, and doubling the opponents costs them very little. It is almost as costly to compete to 3♠ and go down 1 doubled.
Two lessons here:
Now if EW are not vulnerable, doubling for a one-trick set isn’t nearly as profitable, and so not as attractive a risk. Let’s go back to our results where both sides should take 8 tricks.
Now your close double only gains you half a MP, since you still don’t beat those who were allowed to play in 2♠.
How does this all apply to IMP scoring? Well, if you double 3♥, and they make 3 for -730, when your teammates (or the field at IMP pairs) makes only 140, or less, you lose 730-140=590 total points, for -11 IMPs. If they go down one for +200 instead of +100, you gain 200-100=100 total points, for +3 IMPs. Just not worth the risk, unless you expect them to go down at least 2 tricks.
One of my early mentors told me that I had to expect to defeat their part-score three tricks to double them at IMPs, and that was after I dropped a trick on defense.
|7.2 IMP Versus MP — General||7.2.2 Bidding Games|