[jhwva]

A friend and I like to play together with other random people, but the game always used IMPs which we don't understand. Is there a a way to request a table with MPs? I know how to do it if I know all four people involved, but not if I know just my partner? If not, how can I learn how the IMPs are calculated? Thanks

[mycroft]

The host, when they set up the table, selects the scoring method (it's the "Scoring" box right in the top left). That can't be changed without starting a new table. If you like playing MPs, it's likely you'll have to host the table, as most just pick the default, which is IMPs.

Because IMPs is the default, a lot fewer tables run MP scoring, so it is possible that it will take longer to get a full set of comparisons. But it does come up.

"IMP scoring" the Casual game uses is actually "Cross-IMP scoring". In a team game, your score will be added to your teammates (sitting the other direction), and that result converted to IMPs on the standard table (which flattens the big results down somewhat, so a vulnerable slam difference (750) is only 13 times as much as an overtrick (30).) In Cross-IMPs, your score (sitting N-S, say) is added to each of the other tables' E-W scores as if they were your teammates, and the result IMPed. Then those scores are added and divided by the number of comparisons.

But don't worry about that, to read it, just know that + is good, - is bad, and bidding and making games and slams are the key (6-13), overtricks less so (1-2). Try to avoid 800s (unless it's sacrificing against 1430 or 2210!)

[Cyberyeti]

Imps are calculated against other peoples' results using the difference between your result and theirs according to this scale

https://www.bridgehands.com/I/IMP.htm

There are several ways to score pairs events by IMPs, you can either IMP your score against all the others and take the average, or you can create a datum score in your direction by disregarding the top and bottom 1 or 2 scores depending how many pairs sit your way and averaging the rest then IMP against that score.

[mycroft]

Please forget datum! Please. And don't teach anyone new that it existed. It was a great idea from before we had computers, but it is *decades* after it's sell-by date now that it doesn't have to be done by hand. Nobody should ever hear that word (again) :-) Grotty details in spoiler.

Spoiler

Actually, I can't say it any better than I did 8 years ago. The story (because the link is broken, from archive.org):

Quote

A fine example of what the Butler system can lead to was provided in a tournament in Scheveningen early in 1994. The main players are none other than Hamman-Wolff and Leufkens-Westra :

In the last round of that tournament, a board had been scored 2NT+1 : +180. The opponents on the board, Mrss Hamman-Wolff, sought and got a rectification. They expected to gain one IMP and consequently one place, but instead lost one place and 2000 Dutch guilders.

What had happened ? Together with a change of score, this rectification induced a change of datum-score, the average with which all scores are compared. This average fell from +240 to +230.

Hamman-Wolff originally got 240-180 = 60 = 2 IMP
After the rectification, this became 230-150 = 80 = 2 IMP

On the other hand, the Dutch pair of Leufkens-Westra (playing North-South) originally scored 400-240 = 160 = 4 IMP. This became 400-230 = 170 = 5 IMP, gaining them one IMP and a lone sixth place (originally they had been classed equal sixths).

(says the person who many years ago, hand-cross-IMPed a 6-table game. It took about 35 minutes to do each round of 6 boards, which was just about enough time for the next round to finish. The winner was announced in the bar.)

[AL78]

At X-IMPS, you get shafted when you come up against the only pair to bid a cold game or slam.

At MPs, you get shafted when you come up against the only pair to ignore their nine card spade fit and play in 3NT, which happens to make the same number of tricks as 4S thanks to a fortunate lie of the cards.

[mikl_plkcc]

AL78, on 2021-October-05, 02:35, said:

At X-IMPS, you get shafted when you come up against the only pair to bid a cold game or slam.

At MPs, you get shafted when you come up against the only pair to ignore their nine card spade fit and play in 3NT, which happens to make the same number of tricks as 4S thanks to a fortunate lie of the cards.

At X-IMPS, after you get shafted, your session is basically over.

At MPs, after you get shafted, your overtrick next board where no-one else played cancels that out.

[AL78]

mikl_plkcc, on 2021-October-06, 14:53, said:

At X-IMPS, after you get shafted, your session is basically over.

At MPs, after you get shafted, your overtrick next board where no-one else played cancels that out.

I've seen this argument before, and I wonder are there really so many fields that are so strong it is impossible to gain imps to recover from a game or slam swing, but so weak that you can confidently steal an overtrick on the next board?

The truth is that one large swing out isn't the end of your evening, you can get even a vulnerable a game swing back with a couple of partscore swings in, but in both forms of scoring it depends how the cards are dealt. I've had X-imp and teams evenings where it has almost impossible to bring in susbtantial imps, and MP evenings where there has been a massive hand bias the other way, and gaining matchpoints is very difficult with balanced five counts where you are passing and following suit whilst the opponents repeatedly make their cold contracts that hardly anyone else in the room finds*.

*Which is what happened to me on one round on Monday evening. We got four consecutive bottoms, our opponents bid to their best contract and the cards lay perfectly for them. Board 3 I lead 4th highest from a suit headed by KQ against 3NT (why not?), dummy comes down with AJ doubleton, so I blew a trick immediately with a lead from the most promising holding. Of course the other pairs are playing 3NT the other way where the same lead by my partner is deadly. That is the problem with bridge, there is a significant element of luck, so sometimes reasonable decisions get punished, and poor actions get rewarded, so those who played the best don't necessarily win. I sometimes wish bridge was more like chess.

[mycroft]

The converse is:

At X-IMPs, there are probably 4 or 5 key boards in a 26-board session. If you get them wrong, or don't notice that they're key in time, or get unlucky, your session is over.
At MPs, *every board* is key. If you get 4 or 5 wrong, or get unlucky, your session is over.

Frankly, that's what makes MPs so much fun - but also so tiring (BAM/point-a-board team matches even more so).

Sure, it's easier to recover from a few bad boards at MPs if you're a 60% player, where you can pick up half-a-board a round every round instead of all your brilliance being worth 0.5 X-IMPs off your -10.5; but the 60% player is usually the one that "gets them right" (and definitely the one that knows which hands are key) at X-IMPs as well.

[barmar]

mycroft, on 2021-October-07, 09:00, said:

The converse is:

At X-IMPs, there are probably 4 or 5 key boards in a 26-board session. If you get them wrong, or don't notice that they're key in time, or get unlucky, your session is over.
At MPs, *every board* is key. If you get 4 or 5 wrong, or get unlucky, your session is over.

This thread isn't about playing in a tournament with a fixed number of boards. It's talking about playing at casual tables. So the session is as many boards as you feel like playing.

[barmar]

jhwva, on 2021-October-04, 14:59, said:

A friend and I like to play together with other random people, but the game always used IMPs which we don't understand. Is there a a way to request a table with MPs?

If you're talking about using I have a partner. Take us to a table, there's no way to add any criteria. You usually get IMPs tables because those are most common (probably because it's the default when starting a new table).

If you want more control, start your own table and wait for people to come to you, rather than having the system find a table for you.

[mycroft]

Still applies, though. 20% of the hands are worth more than the other 80% at X-IMPs, and one of the skills is knowing which ones they are. Each board at MPs is worth the same as any other; if you pooch 1, it often takes 4 or 5 to recover (whereas at X-IMPs you can get it all back with one lucky result. Or not, with 10 good, but low-scoring, results).

And I answered the OP with my first response. The thread has drifted.