While Rubber Bridge is undeniably a game of skill, the random of deal of the cards can affect the outcome in the short-run, making it unsuitable for large scale competitive play. To circumvent this, Duplicate Bridge is played in clubs and tournaments. Instead of shuffling the cards between each deal, the hands are preserved and played by every pair or team. Then the teams' relative performances are judged. This makes for a much fairer game, where runs of high cards are irrelevant, and every hand can be crucial.
The Basics, Equipment, and Terminology
Duplicate Bridge requires some special equipment in order to work properly, as well as multiple tables and space for players to move around. To keep track of all this, a director is appointed to answer queries, make judgments and ensure that things move smoothly. At the highest levels of play, screens may be used at each table to prevent partners for communicating information through coded gestures.
A session of Duplicate Bridge can vary in length, but it's usual to play between 20 and 30 hands. Before play begins, the cards are shuffled and dealt (either by the players, the tournament organizers, or mechanically). Each hand is placed into a slot in a special card holder known as a board and is kept separate for the duration of the tournament. The boards are marked with a number, the four seat directions, and vulnerabilities for each pair.
After each trick is played, players keep their cards in front of them rather than gathering them all up. At the end of each hand, each player's thirteen cards are placed back into the board. This preserves the hand, so the next players to receive that board will receive an identical arrangement of cards. The player seated North writes the results of the hand onto a scoresheet, known as a traveller. The traveller accompanies the board on its journey around the tournament hall. By the end of the session, the results of every pairs' attempt at the hand will be recorded on it, ready for comparison and final scoring (see below).
After playing a predetermined number of hands (usually three or four), the boards are passed to a new table. In addition, at least half of the pairs will move in the opposite direction. Every pair is assigned a number which is used for scoring and working out where next to move. This rotation of boards and pairs ensures that everyone plays as many different hands and faces as many different opponents as possible, with no repetition.
Bidding Boxes and Convention Cards
Bridge tournaments can have dozens of pairs playing simultaneously. To reduce noise levels, and to prevent players from overhearing the auctions for boards they're about to play, bidding boxes are used. A bidding box contains a set of printed cards, each with a different bid on it. Each player makes their bid by removing the appropriate card and placing it on the table in front of them. The cards are staggered, so making a bid will automatically bring all the lower bids with it, removing them from play. There are also cards to indicate passing, doubling and redoubling.
There are two other cards available to players, marked "STOP" and "ALERT". If a player makes an artificial bid, his partner must alert this to the opposing pair, who are then given the opportunity to ask the alerting player what the bid means. Different bridge organizations have different rules and procedures governing which specific bids need to be alerted.
The use of the stop card is normally optional, but must be used consistently. It is used just before making any jump bid (i.e. a bid that isn't at the lowest available level for the chosen suit).
Because it can quickly become tedious to explain every artificial bid, convention cards are often used. Before the tournament, each partnership marks down all the bidding conventions they use, along with certain cardplay techniques such as leads and signals. The convention cards should be available at all times to be consulted by opponents.
Scoring
While scoring for Duplicate Bridge might initially seem far removed from scoring for Rubber Bridge, it's really just an added layer on top. Like everything about Duplicate Bridge, the aim is to preserve the rules while smoothing out the randomness.
Because each board in a session of Duplicate Bridge is a separate entity, none of the persistent scoring from Rubber Bridge is retained. So there is no rubber bonus and part scores do not carry over from hand to hand. Vulnerabilities are pre-set, with all four vulnerability permutations appearing every four boards. The honor bonuses are also removed, because they'd simply be the same for each pair and cancel out.
To compensate for these changes, there are extra points in Duplicate Bridge for making a game or simply fulfilling a contract that's worth less than 100 points (known as a partial or part-score). These function much like the slam bonuses in Rubber Bridge, which are retained in Duplicate:
| Contracts bid and made: | Not-Vulnerable | Vulnerable |
| Grand Slam | 1000 | 1500 |
| Small Slam | 500 | 750 |
| Game | 300 | 500 |
| Part Score | 50 | 50 |
In addition, the insult bonuses are still present, with a 50 or 100 point bonus for making a doubled or redoubled contract respectively.
The score for every hand is entered into the traveller by North and checked by East. Once all the boards have been played, the scores on each traveller are compared and points awarded. The two systems most commonly used are matchpoints and IMPs (international matchpoints).
Matchpoints
This is the most commonly used scoring system for Pairs competitions (see below). At the end of the session, each score on the traveller is compared with every other. Pairs are awarded 1 point for every pair sitting in the same direction who scored lower than them, and 1/2 point for every pair who scored the same.
These matchpoints are then added up across all boards to determine the winner(s).
IMPs
IMPs is a much more complicated system. At the end of the session, each pair's score is compared with the average (or sometimes every other score) for the board and they are awarded points according to the IMP table. Because of this complexity, this is less popular for Pairs tournaments, where many calculations have to be performed. However, it's the usual scoring system for Teams tournaments, because only two teams have to be compared at any one time (see below).
After each match is finished, the difference in IMPs determines the winner. Alternatively, some events (notably Swiss Teams) convert IMPs into Victory Points to decide the advancing team(s). Victory Points use the margin of victory in each match to gauge each team's performance.
Duplicate Bridge is either played in pairs or teams. Various methods have been devised to ensure that the competition is as fair as possible. The method chosen will depend, among other things, on the number of pairs, the amount of space available, the seriousness of the competition, and the number of winners required.
Pairs - Mitchell Movement
The Mitchell Movement is the simplest and most common system. Every pair is assigned a number and a position (North-South or East-West) which will remain fixed throughout the competition. After each round, the North-South players stay seated while the East-West pairs move to a new table. The boards move in the opposite direction. The aim is that by the end of the session, every North-South pair will have played against every East-West pair, and everyone will have seen every board.
Unfortunately this isn't always possible. In the case of an odd number of tables, everything will work itself out naturally. But with an even number of tables a table must be skipped halfway through the session or the East-West players will run into boards they've already played. The tournament director will make an announcement when this is due to happen, and East-West will miss out on both a set of boards and an opposing pair.
Various alternatives are employed to avoid this situation. The most common is Byestand Mitchell, which requires an extra, unused table where boards sit for one round, but there are a huge number of different tweaks and fixes. If in doubt, the tournament director will help players who get lost!
Because pairs are designated North-South or East-West, Mitchell movements will produce two winning pairs, one from each group. If this is undesirable, perhaps because of prizes, then a more complicated movement is required.
Pairs - Howell Movement
The Howell Movement aims to pit every pair against every other, producing a single winner. As with the Mitchell Movement, every pair is assigned a number, but unlike Mitchell, only a single pair will remain stationary for the entire session. This is usually the North-South pair at table 1, and each other pair will take it in turns to play East-West against them. The other pairs will have to follow the movement schedule, moving to different tables after each round, sometimes playing North-South and sometimes East-West. This schedule will have to be worked out in advance and distributed to each pair. It will vary depending on the number of tables.
Teams - General
A Bridge team consists of 4 players (sometimes more, but only four play at any one time). They're split into two pairs, and one pair sits North-South on one table while the other sits East-West on a second. A second team takes the opposing slots, and each table plays the exact same boards. This allows the teams' performances to be directly compared. There are several ways to manage tournaments with more than two teams, but every approach will involve a series of matches in this format, with two teams playing identical boards across two tables.
Scores are usually calculated using the IMP scale, which is better suited to finding small differences between two sets of players. By contrast, employing the matchpoint system for teams can only produce a score of 0, 1 or 2 for each board. It's only normally used for Board-a-Match tournaments (see below).
Teams - Swiss
In a Swiss tournament, every team plays in every round. After each match teams are awarded victory pointsVictory Points based on their IMPs score, and teams with similar scores are paired against each other in subsequent rounds. The team with the highest score after the final round is the winner. The advantages here are that any number of teams can play, and having a bad round doesn't necessarily mean an overall loss.
Teams - Knockout
As the name suggests, the losing team from each round of a knockout tournament is eliminated from the competition. Surviving teams are matched against each other, often according to a seeding system, until only one team remains.
Teams - Board-a-Match
A Board-a-Match tournament is different from the other team tournaments, because it involves a movement system and a small number of boards per round. In this respect it's much closer to a Pairs competition. As with other team formats, a team will play the same board against two pairs from an opposing team, but after three or four boards the teams will rotate using an augmented Mitchell movement system. Once the session is over, the scores are compared using matchpoints. This can make for a more tense tournament than the other formats, because each board is equally important to the overall score.
