Scoring for Home Duplicate Bridge
Home Duplicate Bridge (HDB) is played by pairs rather than by teams of four. However, it does not use match point scoring. In match point scoring, you get one match point for every team playing in the same direction that you beat, and one-half match point for every such team that you tie. Maximizing overtricks and minimizing undertricks is critical with match points, as is playing in notrump rather than in a minor suit if possible, and this system of scoring provides a rather artificial version of Contract Bridge. Team play in tournaments is much closer to the spirit of rubber bridge (“party bridge”), except for board-a-match contests; International Master Points (imps) or Victory Points (derived from imps) are used, and the emphasis is much more on simply bidding and making a good contract – overtricks aren’t very important.
Therefore the scoring for Home Duplicate Bridge uses imps rather than match points, but your “team” (as, for example here, for a N-S pair) consists of the E-W pairs at all the other tables, taking into account their scores in some sort of average way. Of course, the configuration of these “teams” changes with each round, so you’re playing both with and against all the other pairs during the course of the session. The first step in HDB scoring is to calculate your raw score (in terms of standard bridge scoring) as the difference between what you got on a board and the lowest score in the same direction (i.e., of all the N-S pairs including yourself, if you are playing N-S on this board). Such scoring unduly overemphasizes the values of games and slams, so you convert this raw score to imps, using a nonlinear table which gives increased emphasis to the smaller raw scores. (For example, you get 3 imps for a raw score of 100, but 14 imps, rather than 30 imps, for a raw score of 1000.)
International Match Point Scoring Table
Score |
Imps |
Score |
Imps |
Score |
Imps |
Score |
Imps |
Score |
Imps |
0-10 |
0 |
170-210 |
5 |
430-490 |
10 |
1100-1290 |
15 |
2250-2490 |
20 |
20-40 |
1 |
220-260 |
6 |
500-590 |
11 |
1300-1490 |
16 |
2500-2990 |
21 |
50-80 |
2 |
270-310 |
7 |
600-740 |
12 |
1500-1740 |
17 |
3000-3490 |
22 |
90-120 |
3 |
320-360 |
8 |
750-890 |
13 |
1750-1990 |
18 |
3500-3990 |
23 |
130-160 |
4 |
370-420 |
9 |
900-1090 |
14 |
2000-2240 |
19 |
≥4000 |
24 |
But there is still a problem of overemphasis of the effect of a very bad board (or a very good board) – such a result can overly dominate your score for the session (which doesn’t happen with match point scoring). For team-of-four play in Sectional Tournaments and higher, the American Contract Bridge League now requires a second conversion, from imps to Victory Points, and doing this reduces preponderant influence of the result on any particular board. The two teams’ total imps in a set (of, say, four boards) are compared, and the difference between these two numbers is converted to Victory Points for each team according to a table. Such tables for a given number of boards per set are given on the next page. Again, this conversion is nonlinear, favoring lower imp differences; in fact, there is a maximum number of Victory Points which a team can win in a set of boards, regardless of how well it does for that set. Thus this second conversion, from imps to Victory Points, again mitigates the influence of the result for any particular board, and it also mitigates the influence of doing extremely well against weak opponents for a particular set of boards.
HDB scoring makes a similar conversion from imps to Victory Points, for each set of boards taken as a whole. Your total imps for that set is compared to the average total imps for all the other pairs playing in the same direction (i.e., of all the other N-S pairs, if you are playing N-S in that round). Then the difference between your imp total and the average of the other pairs’ imp total is converted to Victory Points, for that set of boards. Finally, the total number of per-set Victory Points is added up for each pair, to determine the winner.
The following Victory Point scales are suggested for clubs in Bridge Director’s Companion by Larry Harris (Devyn Press, Louisville, Kentucky, 1991). They are different from the official ACBL 20-Point and 30-Point Scales for team matches. “Imps” refers to the difference in total imps between you and your opponent, for a particular set of boards. (In this case, the average imps of the other players sitting in the same direction.) Corresponding Victory Points are given in the second and third columns. If this difference is positive, use the second column, headed “+”; if it is negative, use the third column (“-”).
3 Boards/Set 4 Boards/Set 5 Boards/Set
Imps |
+ |
- |
|
Imps |
+ |
- |
|
Imps |
+ |
- |
0 |
5 |
5 |
|
0 |
7 |
7 |
|
0 |
8 |
8 |
1 |
6 |
4 |
|
1 |
8 |
6 |
|
1 |
9 |
7 |
2-3 |
7 |
3 |
|
2 |
9 |
5 |
|
2 |
10 |
6 |
4-6 |
8 |
2 |
|
3-4 |
10 |
4 |
|
3-4 |
11 |
5 |
7-9 |
9 |
1 |
|
5-6 |
11 |
3 |
|
5-6 |
12 |
4 |
≥10 |
10 |
0 |
|
7-9 |
12 |
2 |
|
7-9 |
13 |
3 |
|
|
|
|
10-12 |
13 |
1 |
|
10-12 |
14 |
2 |
|
|
|
|
≥13 |
14 |
0 |
|
13-15 |
15 |
1 |
|
|
|
|
|
|
|
|
≥16 |
16 |
0 |
6 Boards/Set 7 Boards/Set 8 Boards/Set
Imps |
+ |
- |
|
Imps |
+ |
- |
|
Imps |
+ |
- |
0 |
10 |
10 |
|
0 |
12 |
12 |
|
0 |
13 |
13 |
1 |
11 |
9 |
|
1 |
13 |
11 |
|
1 |
14 |
12 |
2 |
12 |
8 |
|
2 |
14 |
10 |
|
2 |
15 |
11 |
3 |
13 |
7 |
|
3 |
15 |
9 |
|
3 |
16 |
10 |
4-5 |
14 |
6 |
|
4 |
16 |
8 |
|
4 |
17 |
9 |
6-7 |
15 |
5 |
|
5-6 |
17 |
7 |
|
5-6 |
18 |
8 |
8-10 |
16 |
4 |
|
7-8 |
18 |
6 |
|
7-8 |
19 |
7 |
11-13 |
17 |
3 |
|
9-10 |
19 |
5 |
|
9-10 |
20 |
6 |
14-16 |
18 |
2 |
|
11-13 |
20 |
4 |
|
11-13 |
21 |
5 |
17-19 |
19 |
1 |
|
14-16 |
21 |
3 |
|
14-16 |
22 |
4 |
≥20 |
20 |
0 |
|
17-19 |
22 |
2 |
|
17-19 |
23 |
3 |
|
|
|
|
20-22 |
23 |
1 |
|
20-22 |
24 |
2 |
|
|
|
|
≥23 |
24 |
0 |
|
23-25 |
25 |
1 |
|
|
|
|
|
|
|
|
≥26 |
26 |
0 |
©2009 by David Jette