Editing Duplicate bridge (section)

==Scoring==
{{See also|Bridge scoring}}

===Scoring and tactics===
The type of scoring significantly affects a pair's (or team's) tactics. For example, at matchpoints, making one more overtrick than everybody else on a board gives the same result (the top) as making a slam that nobody else bid, whereas at IMP scoring, the difference comes down to 1 IMP (30 points) in the first case, but 11 or 13 IMPs (500 or 750 points) in the second case. In general, matchpoint scoring requires a more "vivid" and risk-taking approach, while IMP scoring requires a more cautious approach. People that dislike IMP scoring sometimes refer to it as "cowardly", while people that dislike matchpoint scoring sometimes refer to it as "not bridge". The main features of the tactics are:
* '''Matchpoints'''
** Overtricks are important.
** [[Safety play]] is often neglected in the hunt for overtricks.
** Thin [[Contract bridge glossary#G|games]] and [[Contract bridge glossary#S|slams]] are avoided.
** [[Sacrifice (bridge)|Sacrifice]]s are more frequent; e.g. going down 500 points on a doubled contract is a good result if the opponents can score 620 points for a game.
** [[Contract bridge glossary#P|Penalty doubles]] are more frequent, as they increase the score for the [[Contract bridge glossary#P|penalty]]. For example, "the magic 200" refers to the situation when a vulnerable pair's contract is doubled and goes one down &mdash; the score of 200 will outscore almost all part-score contracts played at other tables.
** Playing in higher-scoring [[Contract bridge glossary#D|denominations]] (notrump or [[Contract bridge glossary#M|major suits]]) is important, as it may lead to an extra 10 or 20 points.
** Due to the above, it is often unclear to the defence, and sometimes even to declarer, what their goals are.<ref>Kelsey, H.W.: "Match-point bridge", Faber's "Master Bridge Series", 1970</ref> Thus mastering matchpoints play requires additional skills (sometimes referred to as "not bridge" by those who dislike it) to those required to play IMPs.
* '''IMPs'''
** Overtricks are not important, and it is not worth a significant risk of losing a game bonus of 300–500 points = 8–11 IMPs (or to a lesser extent a part score of 110 to 190) for the potential 1 IMP gain for an overtrick.
** [[Safety play]] is very important, for the same reason.
** Thin [[Contract bridge glossary#G|games]] and [[Contract bridge glossary#S|slams]] are often bid. Bidding a [[Contract bridge glossary#G|game]] with 40 percent [[probability]] of success vulnerable and 45 percent nonvulnerable, or a small slam with 50 percent probability, is worth the risk, and anything over that increases the probability of a positive IMP score in the long run.
** [[Sacrifice (bridge)|Sacrifice]]s are less frequent, as they may be risky and the relative gain can be less. Conceding -500 points rather than -620 if you might have got the opponents down for +100 is less worthwhile. However, if you can hold the penalty to -100, this is attractive.
** [[Contract bridge glossary#P|Penalty doubles]] are less frequent, as they may be risky. Often, when an opponents' contract is doubled, it turns declarer's attention to the bad lie of cards, and may induce him to take a successful line of play that he would not take otherwise.
** The contract itself sets a clear goal for both the defence and declarer, frequently allowing a deeper level of counter-plays between them.

===Contrast with rubber bridge===
Duplicate bridge, especially matchpoint games, differs significantly from [[rubber bridge]] in scoring technique, and therefore occasionally somewhat in tactics for bidding and play. Whereas the goal in rubber bridge is to win more points than the pair of people you are playing against, in duplicate bridge the goal is to do better than other pairs playing exactly the same cards. Because of this, strategies are different. In rubber (as in IMP scoring), 30 points above the line for an overtrick is unimportant and hardly worth risking a set. In match-points duplicate, it is common for those 30 points to mean you get a top score instead of average &ndash; and may be worth risking going down. In rubber, an occasional 800-point penalty is disastrous, but in matchpoints it is no worse than any other bottom score. International match points is in the middle of these extremes. Huge penalties are worse than small penalties, but 30 point differences are only moderately important.

A more subtle difference is in the bidding of [[Contract bridge glossary#P|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 unique advantage of largely neutralizing a run of bad luck with the cards because a pair that has had poor hands all night may still have the highest score for the session{{snd}}as long as they play their cards more skillfully than the other pairs with the same poor hands. That said, in such cases these pairs will probably have had fewer opportunities to exercise those skills, and their results may depend more heavily on the expertise of their opponents.