7.2 IMP Versus MP — General

One topic that seems to puzzle many learning players is the difference between International Match Point (IMP) and Match Point (MP) scoring, and how that affects your tactical decisions. Since this is a huge topic, I’ve undertaken to discuss it over a series of newsletters.

Here’s the short course on the difference in scoring between IMPs and MPs.

At IMP scoring what matters is by how much you beat the other scores. A difference of 10 points between 620 and 630 for 4♠ making 10 tricks, or 3NT making the same 10 tricks results in no IMPs changing hands. In an IMP pairs game, you compare your score to each of the others in your direction, and come up with a difference of total points. You then look up this amount on an IMP (International Match Point) scale, and convert to those. This is done to make the numbers smaller, and easier to deal with. Then you will add up all the IMP scores, and divide by the number of pairs.

Here’s the IMP scale:

International Match Point Scale
Difference	IMPs	Difference	IMPs	Difference	IMPs	Difference	IMPs
20-40	1	270-310	7	750-890	13	2000-2240	19
50-80	2	320-360	8	900-1090	14	2250-2490	20
90-120	3	370-420	9	1100-1290	15	2500-2990	21
130-160	4	430-490	10	1300-1490	16	3000-3490	22
170-210	5	500-590	11	1500-1740	17	3500-3990	23
220-260	6	600-740	12	1750-1990	18	4000+	24

Now, at MP scoring, you get one Match Point for each score you beat, no matter by how much, and half a Match Point for each score you tie. So, now the 10 point difference can make a very large difference in your score. Here’s a sample of a possible set of scores for an 8-table game of matchpoints.

Table	Contract	By	Result	NS+	NS-	MP Score
1	4♠	N	+1	650		7.0
2	3NT	N	+1	630		5.5
3	3NT	N	+1	630		5.5
4	4♠	N	=	620		3.0
5	4♠	N	=	620		3.0
6	4♠	N	=	620		3.0
7	3NT	N	=	600		1.0
8	5♠	N	-1		100	0.0

On OKBridge these scores are converted to percentages, but they are still calculated by thie method before conversion. 7MP is 100%, 5.5 is 68.75%, 3 is 37.5%, 1 is 12.5% and 0 is 0%.

Not so mysterious after all. For today, we’ll leave it that at IMP scoring you want to avoid the big minus scores, and bid your games to get the bonus. At MP scoring, however, you need to fight for every point, choosing the highest scoring contract and often going for risky overtricks.