As with matchpoint scoring, the most important thing about IMP scoring is not how the scores are calculated; rather, it’s about how the scoring system affects strategy. When playing at IMPs, winners take risks that stand to produce big wins (think ‘home run’ and ‘risk being thrown out at home plate’ in baseball terms) and avoid risks that stand to produce small wins (think ‘singles’ in baseball terms). IMP events typically are won by these sorts of big scores:
- You bid and make a game; at the other table, they stop in a part-score. You win ten IMPs if you’re vulnerable and seven IMPs if you’re not vulnerable.
- You bid and make a slam; at the other table, they stop in game. You win thirteen IMPs if you’re vulnerable and eleven IMPs if you’re not vulnerable.
- You score a big penalty. For example, if you score plus 800 instead of plus 420, you gain nine IMPs. If you score plus 1100 instead of plus 140, you gain fourteen IMPs.
And these sorts of modest scores also matter:
- Your team makes small part-scores at both tables. Plus 110 at both tables gains six IMPs (almost as much as a non-vulnerable game swing).
- You make plus 800 instead of plus 620, gaining five IMPs.
On the other hand, although it’s an overstatement to say that overtricks don’t matter at IMPs, they don’t matter much. Plus 130 versus plus 110 is only one IMP.
We will stop there; the mechanics of IMP scoring are interesting, but in The Real World, we’re not interested in mechanics; instead, we are interested in strategy.