Cross IMP scoring is used in many events, including the McDonald, Calder/Martin, and Grindon.
Cross IMP scoring is teams scoring for pairs. It is a method that has only become popular with computer scoring since the calculations are extensive, but the strategy is exactly the same as teams and aggregate scoring. Bid your games aggressively, beat the opponents’ contracts, overtricks are not that important.
I’m often asked what a good score at cross imps scoring?
The simple answer is to say the same as a good score in the Scott Cup or Tom Woodman teams. Which for most people is more than the other teams, it’s just difficult to predict since it depends on the boards and who you play them against. If you bid and make a lot of games, you will get a good score.
In general, if you average more than 1 imp per board then you are having a very good game.
One imp per board does not sound very much, as it is only an overtrick on every board.
Small differences, such as the difference between +100 or +110, will be largely irrelevant (unlike matchpoint pairs). It is winning partscore battles, making games, and making slams that will determine your score.
In world-class teams events, cross imps scoring is used to produce the ‘butler’ and the best pairs tend to average around +0.75 imps/board. In a more mixed field, you will typically see the best pairs average about +1 imps/board.
However Michael Clark from the EBU reported that “the average score for second place in almost 3000 cross-IMPed EBU sessions is 1.323 IMPs/board. So try to score 1.324 IMPs/board and you'll win!”
So aim for +1 imp per board and, over the season, you will do well.
Read Paul's full article here (PDF).