Sacrifice (bridge)
Sacrifice is, usually a deliberate, bid of an unmakeable contract in contract bridge in the hope that the penalty will be smaller than the value of an opponents' contract. In rubber bridge, a sacrifice can be also made in an attempt to prevent the opponents to score a game, hoping that the cards in subsequent deals will turn the side and provide a compensation.
In bridge scoring, making a game yields approximately 620 points vulnerable and 420 points non-vulnerable. As the opponents will often double the sacrificial bid, it will turn out profitable if it commences less points; 3 and 2 doubled undertricks when the sacrificing side is non-vulnerable cost 500 and 300 points respectively, and 2 vulnerable doubled undertricks cost 500 points. Similar reasoning can be drawn for slams and partscores.
A sacrifice most often occurs when both sides have found a fit during bidding (8 cards or more in a suit), but the bidding indicates that the opponents can make a contract. Also, it is possible to perform an advance sacrifice, when it is more or less clear that the opponents have a fit somewhere and outweight the strength. For example, after the partner opens 1♦ and RHO doubles, the following hand is suitable for a bid of 5♦, outbidding opponents' major suit game in advance:
♠83 ♥4 ♦Q108542 ♣QJ64
Vulnerability significantly affects the sacrifice: statistically, the success is most likely in the situation the opponents are vulnerable but the sacrificing side is not. At equal vulnerabilities, sacrifices are less frequent, and vulnerable sacrifices against non-vulnerable opponents are very rare (and often not bid deliberately, but in an attempt to make the contract). Also, the scoring method affects the tactics of sacrifice – at matchpoint scoring, -500 or -800 (down 3 or 4) against -620 is a 50/50 bet on a top or a bottom, but at IMPs it can gain 3 IMPs (120 difference) but lose 5 (180 difference), making it less attractive.
Law of total tricks can be a guideline whether the sacrifice can be profitable or not.