A way to score pairs’ events in IMPs. You start by averaging the scores for each board to produce a datum, ignoring the top and bottom scores. You then compare each pair’s score with the datum and convert it to IMPs.
For example, if the remaining North-South scores are +600, +600, +600 and -200, the datum is +400. The three pairs with +600 have done 200 better than the datum and score 5 IMPs each. The pair with -200 has fared 600 worse than the datum and scores -12 IMPs.