|2||- 1 -||-600||+1|
|4||- 3 -||-600||+1|
|6||- 5 -||-600||+1|
|8||- 7 -||-630||-4|
|10||- 9 -||-600||+1|
Let us consider the example we used before. In a contest of 10 pairs the contract is 3NT at all tables. Everyone
just makes this contract, except one pair who make an overtrick. At MP's this meant a top (8 MP, and a 0 for the
At cross-IMPs there are 4 scores to compare with, each of them yielding 1 IMP, for a total score 4 for the pair who managed to get an overtrick, and -4 for their opponents. At the other tables all pairs score +1 or -1 IMP. Pairs who play in the same compass direction as the one strong pair score -1, 1/4 of the score of the pair who had a direct encounter with the strong pair.
You probably have already identified the number 4 (i.e. the number of comparisons on which the cross-IMP score is based) as h, half a top at MP-scoring, or, the number of times - 1 the hand is played. Again we notice that the effect of a direct encounter is h times as large as playing in the same compass direction. This is equally true whether the difference is one trick, as in this example, or whether we have a swing hand where both sides can make game. Also, it does not matter whether or not the Cross-IMP score is calculated as an average, i.e. the XIMPS we used here divided by the number of times a hand is played. In all cases we have:
Also in cross-IMPs playing once against an opponent is equivalent to h times playing in the same compass direction. The techniques we used to obtain an optimal balance are also valid for cross-IMPs.
Conclusion: For cross-IMPs just use the same movements as for MP's.