IMP Scoring v Match Point Scoring

30 Apr 2011


Scoring at IMP

In standard pairs scoring, you score 2 points for every pair you beat and 1 for
every pair with whom you tie. If yours is the best score, it doesn’t matter if you
beat the others by 10 points or 200, you still score a “top”

If there are a very small number of tables (say less than four) this can end up being a
bit of a lottery. An alternative is to use IMP (International Match Point) scoring. This
is the type of scoring used in teams matches. With IMP scoring, it is the amount by
which you beat the opposition which is significant.

Here are a couple of examples

Board 1
NS EW Contract by NS EW
1 2 3NT+1 N 430  
3 4 4H= S 420  
5 6 4H= S 420  

In normal pairs scoring, pair 1 would get a top (4 points)
and the others would receive 1 each.

At IMP, this is a “flat” board. Everyone would score zero because
the difference is only 10 points which is considered insignificant at IMP.
Board 2
NS EW Contract by NS EW
1 2 4H= N 420  
3 4 2H+2 S 170  
5 6 2H+2 S 170  

In pairs scoring, this board would score exactly the same as the first
one - a top for pair 1 and tied bottom for everyone else. 

At IMP, pair 1 beat both the others by 250 points which equates
to an IMP score of 6.  Pair 1 therefore score 12 and the others
both -6.

IMP scoring therefore calls for slightly different tactics:

Pairs scoring IMP scoring
Unless you fear an unstopped suit, or think you can make extra tricks by ruffing,
it’s better to play in No Trump than a suit contract. The extra 10 points
could make the difference between a top and an average. 		Always play in the safest contract. That usually means preferring, say,
4 Major to 3NT. The 10 point difference (assuming both are just making)
is totally irrelevant.
Try to make as many overtricks if you can. Overtricks aren’t important. Never risk your contract for
overtricks, no matter how likely they seem. If you make one overtrick
that may earn you 1 IMP. If you go off in a part score when everyone
else is making, that will cost you in the region of 4 to 7 points (depending
upon vulnerability etc.). Go off in a makable game and you could be
looking at a score of -13!
Be “trigger happy” with the doubles. If the opposition will
probably go off, then double. It may even be worth doubling if
you think they’ve found a game or slam which no one else will. If they
are making, they get a top anyway so the double costs nothing.

Doubling a making contract can be expensive. For example, suppose they bid a
non-vulnerable 4© and you double.
If they go 1 off, the double buys you an extra 50 points,
or 2 IMP. If they make, the double has cost you 170 points or
5 IMP. If they make overtricks, you had better resign yourself to the
wooden spoon now.

Generally, you stand to lose more than you stand to gain by doubling. A good
rule of thumb is “only double if you expect to take the contract at
least two off”.
Go for game, small or grand slam if you think it is more likely than not.
Vulnerability makes no difference.

Go for “thin” games, particularly vulnerable.

If you bid game and the others don’t, non vulnerable, if you make it you
gain +6 IMP; if it goes off you only lose 5.
Vulnerable, the scores are +10 if it makes and -6 if it goes one off.

The odds are roughly as follows:

Go for If the odds are
Non vul. game 50% or better
Vul. game 40% or better
Small slam At least 50%
Grand slam At least 66% in your favour. If in doubt, settle
for small slam.