[PL53]

How are the running IMPS, displayed continuously while playing, calculated?

[paulg]

PL53, on 2020-May-08, 04:48, said:

How are the running IMPS, displayed continuously while playing, calculated?

On each board, your score is compared with every other table that has played the hand; this will be a maximum of 15 other tables. Your imp score for the board is the average of the 15 imp scores you get with this comparison and is known as cross imps.

The scores on a board can vary until it's been played 16 times.

It is like playing teams. Bid your games, beat their contracts, overtricks are normally less important.

[mythdoc]

paulg, on 2020-May-08, 05:45, said:

It is like playing teams. Bid your games, beat their contracts, overtricks are normally less important.

It’s only a little like playing teams, actually. The whole point of IMPs is making a Bidding or play decision against a single other table, not against a field. This is a hybrid of matchpoints with the IMP scoring table superimposed over the top of a field result. It’s fine I suppose for practicing for an upcoming actual IMPS match, when the pressure is much higher.

[Vampyr]

IMP pairs can best be described as playing a team match where your teammates are the worst pair in the room.

[mycroft]

...where your teammates are *every other* pair in the room.

Which I will admit isn't fun for those top-flight pairs that don't get to pick their choice of teammates, they have to score with (among others) my partner and me. But it's the same for "the worst pair in the room", who get a better class of teammates (on average) than they would be able to pick up for the team game.

I enjoy it occasionally; we play it (in flight A only) one session at our sectionals, and once a month or so in one or two clubs. As a steady diet, I would find it wearing. But it's not that much worse than "Connor MacGregor and Evander Holyfield in a room full of drunks and the winner is the one who can knock out the most" - I mean, "Matchpoint Pairs" - especially in the BBO club where your scores are compared against a random 15 pairs from champions to incompetents (or drunks, or drunk champions!), and a different 15 pairs on each hand.

[barmar]

mycroft, on 2020-May-08, 14:54, said:

...where your teammates are *every other* pair in the room.

I think Vampyr's point is that a single outlier pair can significantly skew the IMPs.

Suppose game is obvious and cold. If everyone bids it and makes the contract, possibly with an overtrick or two, you'll all get between -1 and 1 IMP, similar to a team game where the opponents and teammates are of the same calibre.

But suppose one pair (the hypothetical worst pair in the room) fails to bid game, or manages to find a way to go down. Now that one pair gets -10 IMPs (and their opponents get a windfall), while everyone else just gets a fraction.

But is this really so bad? Much of IMPs strategy is that overtricks are not that important, the critical thing is to make your contract (when declaring) or set their contract (when defending). IMP Pairs emphasizes this: overtricks fall into the noise when there's a big spread of results.

[Vampyr]

barmar, on 2020-May-08, 16:11, said:

I think Vampyr's point is that a single outlier pair can significantly skew the IMPs.

Suppose game is obvious and cold. If everyone bids it and makes the contract, possibly with an overtrick or two, you'll all get between -1 and 1 IMP, similar to a team game where the opponents and teammates are of the same calibre.

But suppose one pair (the hypothetical worst pair in the room) fails to bid game, or manages to find a way to go down. Now that one pair gets -10 IMPs (and their opponents get a windfall), while everyone else just gets a fraction.

But is this really so bad? Much of IMPs strategy is that overtricks are not that important, the critical thing is to make your contract (when declaring) or set their contract (when defending). IMP Pairs emphasizes this: overtricks fall into the noise when there's a big spread of results.

It’s more that you can’t rely on the pair in the other room to, say, bid a slam that the opponents got to. Usually a number of pairs will not reach it, so you will get a very poor score. Similarly if you get doubled in a good contract that nevertheless goes down. And this board could decide the entire session. Yes, of course you will, as you say, get a good score if your opponents do something stupid. But this is something you cannot rely on.

[paulg]

Cross imp scoring is hugely popular on BBO, almost certainly because most users do not know how to change the default setting. If the default were matchpoints, then it would be more popular. A quirk of history.

If you bid a game at cross imps at most tables, then you will normally score +2 imps even if it is a boring board. So if you feel that the standard of your table is above the average for BBO, then you may feel shortchanged playing in such an environment where the balance of the cards seem to be more important than your decent play.

In such circumstances you should use the Deal source to change the boards from Random to Vugraph. You will now play boards used on vugraph and have comparisons with just the two tables who played the board. In general this means a better standard of comparison but it is not a panacea. Players on vugraph are not immune from making mistakes, bidding slams missing two aces, etc. Vugraph has world-class tournaments but also junior events, some club events with a lower standard, and some Scottish players trying to play bridge at the Camrose Trophy. A small number of vugraph records are also corrupt, leading to senseless comparisons. But overall it is vastly superior.

[rahulc]

paulg, on 2020-May-09, 01:14, said:

Cross imp scoring is hugely popular on BBO, almost certainly because most users do not know how to change the default setting. If the default were matchpoints, then it would be more popular. A quirk of history.

I hate matchpoint pair scoring yet 99% of my bridge play has been forced to be that way (live, ACBL-land). Are there IMP pairs tournaments on BBO? The only ones I've noticed tend to be robot and/or individual. Tried searching for "IMP" in the various tournament types (ACBL, BBO points).

[johnu]

rahulc, on 2020-May-14, 22:11, said:

I hate matchpoint pair scoring yet 99% of my bridge play has been forced to be that way (live, ACBL-land). Are there IMP pairs tournaments on BBO? The only ones I've noticed tend to be robot and/or individual. Tried searching for "IMP" in the various tournament types (ACBL, BBO points).

You can play IMPs in the main bridge club. It's not a tournament as players can join and leave at any time and be replaced. You can join a team game (or if you have 7 friends, you can start your own team game). And there have been a number of knockout events that have been set up but you need to join or start a team. Check out Bridgewinners.com where the tournaments are usually announced.

If you want to play with GIB bots, there are ACBL IMP tournaments for $1.25 as well as BBO tournaments at $.29. There are also some free IMP tournaments on the Free Tournament page.

[rahulc]

johnu, on 2020-May-14, 22:54, said:

You can play IMPs in the main bridge club. It's not a tournament as players can join and leave at any time and be replaced. You can join a team game (or if you have 7 friends, you can start your own team game). And there have been a number of knockout events that have been set up but you need to join or start a team. Check out Bridgewinners.com where the tournaments are usually announced.

If you want to play with GIB bots, there are ACBL IMP tournaments for $1.25 as well as BBO tournaments at $.29. There are also some free IMP tournaments on the Free Tournament page.

Yes, I've played in a bunch of the Reynolds KOs (among my top bridge experiences!). Main club is not so great - I'll only play when I have a party of 4 but still the comparisons can be odd. Didn't see any IMPs in the paid tournaments, but there are some in free. Tried one, will try again with a regular partner.