Duplicate bridge is the most widely used form of bridge used in tournament settings, and is also played in many bridge clubs. It is called "duplicate" because the same bridge hand is played multiple times, using boards to keep and pass each player's hand intact. Final scores are calculated by comparing your results with others who played the same hand.

The overall USA organizations are:

• American Bridge Association (http://www.americanbridge.com)
• American Contract Bridge League (http://www.acbl.org)
• United States Bridge Federation (http://www.usbf.org)

In duplicate bridge, a player normally plays with the same partner throughout an event. The two are known as a "pair". There are two exceptions: on team events with five or six members swapping partners for portions of the event, and in individual tournaments, in which players change partners for each round.

Contents

1 Matchpoint Pairs Game 2 Team Game 3 IMP Pairs Game 4 IMP Tables 5 Individual Events 6 Contrast with Rubber Bridge

Matchpoint Pairs Game

The most common form of pairs game is the matchpoint pairs game.

In a matchpoint pairs game, each deal is played a number of times, after which all the scores are compared. Each partnership scores 2 matchpoints for each other partnership that scored fewer points with the same cards, and 1 point for each partnership that scored the same number of points. These matchpoints are added to determine the winner. Scores are usually given as percentages of a theoretical maximum: 100% would mean that the partnership scored more than every other partnership on every single hand.

[Note: in the United States, scoring is 1 point for each pair beaten, and one half-point for each pair tied.]

Team Game

In a team game, two pairs normally constitute a team. (Teams of five or six members are sometimes permitted, but only four members play at any given time.) Two teams compete using two tables and having one pair from each team seated at each table, at opposite directions. (For example, team A may sit North-South at table 1 and East-West at table 2; then team B would sit East-West at table 1 and North-South at table 2.) A relatively larger number of boards are played (usually six to eight for "Swiss teams", usually 12, 24, or more for knockout events). The boards are moved (usually by a caddy) so that they are all eventually played at both tables.

Suppose Team A plays Team B. The first time a hand is played, one partnership from Team A takes the North-South cards and one partnership from Team B takes the East-West cards; when the hand is played again, it is played by the other two partnerships, but this time with Team A holding the East-West cards and Team B holding the North-South cards. Of course the teams may not discuss the deals between the two plays. After each deal has been played twice, the scores per deal are compared, and a score is given depending on the net total score from the two times the deal was played. For example, if one pair scores +1000 on a deal, and their teammates score -980, then the team's net score on that deal is +20.

One of two forms of scoring is then used to calculate the winner. At "board-a-match", each hand has equal weight; each hand is won, lost, or tied. At IMP scoring, the difference is converted using a scale of 0-24 IMPs (International Match Points) that compresses big differences in score.

IMP Pairs Game

IMP pairs games are played the same way as matchpoint pairs games, but the scoring uses the IMP tables to make big differences in the results at the table also yield big differences in the results. At matchpoints, if a pair makes one more overtrick than everybody else on a board, or if they make a slam nobody else bid, she gets the same result. At IMP scoring, the slam is given more points.

There are at least two methods of using the IMP tables to score a board in a pairs event. One is to take the IMPs against the average score on the board, excluding the top and bottom result. This is often called Butler Pairs scoring. Another is to take the IMPs difference against each other play of the board, or Cross-Field IMP Pairs.

IMP Tables

There are many different IMP tables. A sample 24-point IMP table is:

Point           IMPs
difference  	
0 - 10 	        0
20 - 40 	1
50 - 80 	2
90 - 120 	3
130 - 160 	4
170 - 210 	5
220 - 260 	6
270 - 310 	7
320 - 420 	8
370 - 420 	9
430 - 490 	10
500 - 590 	11
600 - 740 	12
750 - 890 	13
900 - 1090 	14
1100 - 1290 	15
1300 - 1490 	16
1500 - 1740 	17
1750 - 1990 	18
2000 - 2240 	19
2250 - 2490 	20
2500 - 2990 	21
3000 - 3490 	22
3500 - 3990 	23
4000 or more 	24

[1] (http://www.acbl.org/learn/scoreTeams.html)

Individual Events

An individual event in duplicate bridge is one where each round a player is paired with a random partner. Scoring is usually using matchpoint pairs scoring, but IMP pairs scoring can be used.

Contrast with Rubber Bridge

Duplicate bridge differs than rubber bridge because whereas the goal in rubber bridge is to win the rubber, in duplicate bridge the goal is to get a better score than the other people playing the same cards in the same direction. Because of this, strategies are different. Even within duplicate bridge, there are generally two different scoring methods: match points and international match points (also known as IMPs). In match points, you get the number of points equal to the number of other pairs you have beaten, and in IMPs the number of points corresponds to the difference in scores between you and the other pairs.