How to decide if you are an IMP or MP player

The key to being a matchpoint player is working out the *actual* contract when dummy comes down. Not what the table *bid*, but what we are trying to beat.

At non-matchpoint scoring this is obvious when you are preempting/sacrificing; "I need to set it *this much* to beat the game I could make" (conversely, "I need to make this many tricks to beat their game"). In most other cases, the contract played is the contract bid - witness all the "do everything to set the contract, including give away overtricks if the cards are wrong this time" (conversely, "if you have a 100% line to make the contract, do so, even if there's an 80% line to make an overtrick - if the other 20% of the time you go down") advice to new IMP players.

At matchpoints, you have to do this *every hand*, and much less commonly is the contract bid the contract that is being played. Those who are happy when partner makes their contract (even if it's 2♠= when the overtrick is "automatic") and "nice try, opps" when they set us (even if 3♦-1 scores really well against their 2 or 3♠ making) should play IMPs (IMP Pairs, specifically) where their way of seeing the world doesn't cost as much.

Please note, this is *really hard*, and frankly most A players (okay, me) can't do it well. But the better you get at it, the better your matchpoint play will be. The 45% players usually have one or two hands where they missed their game/slam, sure; but the reason they're 45% instead of 54% is the many many hands they pitched a trick in the "normal" contract - but still made or set it!

Again, if this makes no sense to your friend, they shouldn't play MPs (given a choice) until it does.

The other key to matchpoints (very similar to the first one) is "frequency vs cost", "your potential loss (and win) is limited", and the "every hand is worth the same" ideas. I had someone tell me "I've never gone for 1400 before". Yeah, it was a zero, but 800 would have been the same zero, and if they've never aimed for 500 and gone 14, then they've not competed anywhere near enough and have a large number of -620s where others got -500 - or, frankly, a large number of -120s which could have been -50 or even +110, but could, on the wrong hand, have been -1100. If it works three times as often as it doesn't, even if when it works it goes from 35% to 65% and when it doesn't, it goes from 50% to 0%, it's still a winning matchpoint strategy. But "lose 14" is going to be hard to recover from, when you're getting it back in "win one"s and the odd "win five".

Now obviously, if you're going for 1400 every session, you're not going to win at matchpoints either.

Again, if this doesn't make sense, then maybe matchpoints isn't for this player (yet). But they should play a few of them, occasionally, and review the results with these thoughts in mind and look for where their average-minus (25-45%) scores come from. Things will start to make more sense, in time.

And - as someone who was told many years ago that I was not a matchpoint player because I pitched tricks all over the place, and got better at it over time - as you see and as you adjust and as you see the results of your learning come in, it can make matchpoints an *amazingly fun* game.

Oh, two other quick non-bridge reasons why one would play MPs instead of IMPs:

Most FtF IMP bridge are team games. If "disappointing 3 people, not just partner" is anxiety-inducing for you (or if your teammates are the type that will react badly and induce said anxiety when you bring back a bad card), that's an incentive to not play team-of-4. Note this doesn't apply to BBO which has a lot of IMP pairs games (and always has; and the default scoring in the main room is cross-IMPs).
IMP pairs has been called a "crapshoot" by many (expert, but usually wannabe expert as an excuse for why they don't win), because out of the 20-some boards you play in a session, maybe 5 or 6 score more than the rest combined. And if you play those against good pairs (and others play them against the weaker pairs), you can be 20 IMPs behind the field with no chance to catch up. Yes, there is more luck; and yes, knowing "which boards matter early" is an IMP skill; but it's the game you signed up for...

Metrics? No. Sorry. There is no simple rule to apply, at least not without playing sufficient bridge to see which format has you performing better.

When your skill increases to the point where you will make decisions about which finesses to take, which ones to avoid, BECAUSE of the scoring? Which games to bid, and when to choose 3NT versus 4 of a major, or 5 of a minor? When is a preempt a good or bad idea at IMPs versus matchpoints? When you will find safely plays to insure your contract makes against any position of the cards, even if at the possible cost of a trick? When you should be competing in the bidding for a part score, or not?

But if you are not at a point where you are correctly making decisions like the above, then don't worry about the scoring so much. Play whichever makes you happy, whichever scoring form seems more fun to you. And since all of these games tend to be stratified, when you are a relative beginner, it won't matter quite so much anyway.

My personal guess is that IMP pairs is a format that scares novices, because one -14 IMP board can kill an otherwise decent 12 board game. And new players will far more easily be -14 IMPs than +14 IMPs. And if this means there are more low strat players in the matchpoint games, then stratification gives you better chances to come in the money. That sounds as if it is a factor from your question.