- Wednesday, June 4, 2014 16:35,
- by Pat Clark
Duplicate bridge is a variation of contract bridge played at our Club. It is called duplicate because the same bridge hands are played at each table and scoring is based on relative performance. In this way, every hand, whether strong or weak, is played in competition with others playing the same cards, and the element of skill is emphasized while the element of luck is deemphasized. Duplicate bridge is in contrast with rubber bridge, where each hand is freshly dealt and where scores may be more affected by chance in the short run.
In duplicate bridge, a player plays with the same partner throughout an event. The two are known as a "pair."
|Hand carriers, or "boards"|
Final scores are calculated by comparing each pair's result with others who played the same hands. Furthermore, games are "stratified," meaning a pair's performance is measured against other pairs with similar levels of experience. In addition, we frequently hold Novice and Beginner games, where highly experienced pairs are not allowed to play.
Bidding boxes are used to facilitate the mechanics of bidding and minimize the noise level. There is an article about Bidding Boxes here.
|A bidding Box, 4 are used at each table|
Each game is overseen by a Game Director, a sort of referee who seats the pairs, and directs which hands are played when. The Game Director also enforces the rules, which are a little different than rubber bridge. The rules have been established by the national organization, the American Contract Bridge League, or ACBL.
|A scoring unit|
The usual form of overall scoring is Matchpoint scoring. Every pair plays against a number of opposing pairs in successive rounds, depending on the size of the field. Games with up to about a dozen tables are usually played either as a Mitchell movement (each North/South pair plays against all or most East/West pairs) or a Howell movement (each pair plays against all or most other pairs, and switches between North/South and East/West as required). A Howell movement is typically used if there are fewer than about 7 tables. With larger fields the game can be split into separate sections (every section operates its own separate movement, but the scores are compared across all sections); each section normally plays a Mitchell movement.
The game consists of a number of rounds, which each round playing a number of boards, usually two to five, against the same opponents. After each round, some or all of the players move along to another table, according to a prescribed movement, so that each pair plays against a different pair in each round; the boards are also moved in an opposite direction. The movements are set up so that no pair plays more than one round against the same opponents, and, of course, no pair plays the same board more than once. The Game Director will select the movement depending on the number of pairs playing, to allow them to play the desired number of boards each, without repetition. A session typically consists of between 24 and 28 boards in total, but this can vary.
Typically, 7 or 7½ minutes are allowed per board, with hospitality breaks every hour or so. A typical session will thus last about 3¾ hours. If there is an odd number of pairs, one pair will have to sit out in each round.
The Mitchell movement is the most common. The North-South pairs remain stationary. After each round, the East-West pairs move to the next higher table and the boards move to the next lower table. If the number of tables is odd, every E-W pair will play different boards against every N-S pair after the full circle. In case of an even number of tables, the East-West pairs are told to skip a table after about half the rounds so that they do not encounter boards that they have already played; alternatively ("Relay-bystand Mitchell"), a "bystand" (playerless table) is introduced, while the two tables farthest from the bystand share the boards from each round (the "relay"). Usually, the bystand is placed halfway through the field (e.g. between Tables 5 and 6 if there are 10 tables) and the relay between Table 1 and the last table. The "perfect" Mitchell is seven, nine, or thirteen tables, with four, three, or two boards per round respectively: all players play all boards, and all pairs of each direction play against all pairs of the other direction.
|Sample Howell Guide Card|
Whatever movement is used, if the number of pairs is odd, obviously one pair must sit idle during each round; that situation is referred to as a sit out. In that undesirable case, the missing pair (sometimes called the phantom pair) is treated as if it exists, i.e. the movement is set up for one more pair, requiring half that number of tables. The phantom pair may be North-South, East-West or an arbitrary pair number in a Howell movement.
Compared to rubber bridge
|Scores of a Duplicate Game|
A more subtle difference is in the bidding of partscore hands. In duplicate bridge, once a pair recognizes that they are playing for part score (less than a game), their objective is to win the auction with the minimum bid. In rubber bridge, it may occasionally be desirable to bid above this minimum as points below the line may be needed to complete a game.
Duplicate bridge also has the distinction of compensating for a bad run of luck with the cards. A pair that has had poor hands all night may still have the highest score for the evening – as long as they play those cards better than the other pairs with the same poor cards (however in such cases the pair will probably have had less opportunity to exercise skill and their result will be more heavily dependent on the skill displayed by their opponents).
See also: Are you new to Duplicate Bridge?
See also: ACBL's Introduction to Duplicate