Duplicate Bridge – Explanation and Guidelines

Duplicate Bridge  

When you play at a bridge club, the cards are placed in a board so that the same hand can be played many times.   When a table has finished playing a hand the North player fills in the score on the traveling score sheet (traveller) that accompanies the board.   If you are sitting N/S you are hoping to get a higher score than the other North/Souths who have played the same board.  If you are sitting E/W you are hoping to beat the other E/W scores.

Below is a sample bridge traveller for Board 1 in a seven table competition (fourteen pairs).   At the end of the competition the director (or scorer) awards match points (the figures in red) for each board as follows:

A pair gets 2 points for each pair (playing in the same direction) who they beat and 1 point for each pair with whom they equal.

In this example N/S Pair 4 got the best score by playing in 3NT and making two overtricks.  They beat all the other N/S scores (six other pairs) and so score 12 match points    (This shows the importance of overtricks!)

E/W pair 14 got the best E/W score as they were the only E/W pair to defeat the N/S contract.

When the match points have been calculated for each board they are then transferred to a result sheet or ‘recap sheet’ and the total match points for each pair are calculated for the session (these days this is almost always done by the scorer inputting the scores into a computer bridge scoring program rather than writing on a recap sheet).

For the final results sheet, the match point scores are converted to a percentage.   The percentage is the actual match points scored out of the possible maximum match points.

In this seven table competition the maximum match points on a single board is 12 (6 x 2).  So the maximum match points possible is 12 x 14 boards = 168.

Scoring

THE TRAVELLER

It is North's job to write the score on the traveller.  When the traveller has the N/S pair number pre-printed is is very important to make sure the score is entered on the right line.  North always writes the score on the line that is his or her pair number.  When North has finished entering the score, North should show the traveller to East.  East is responsible for checking that all the score details are correct.

Etiquette

THE PLAY

Always count your cards before playing – if someone has the wrong number of
cards the director can sort it out before the hand is played.

Make the opening lead face down.  This is to make sure that if the lead is accidentally made from the wrong side it can be corrected before anyone sees
the card.

The board should be left on the table during the bidding and play of the hand
so everyone can see the vulnerability.  North is in charge of the boards.

Don’t make any comments during the bidding or the play that might give unauthorized information to your partner.

MISTAKES

Always call the director if something goes wrong, e.g. a revoke, wrong number of cards, lead from the wrong hand etc.  The director is there to help sort things out and make sure everything is fair.  Everyone makes mistakes from time to time and there is a rule to cover all kinds of errors.   

COURTESY

Always be polite and courteous to your partner and opponents.

Never criticise your partner (or opponents) or offer advice unless asked. Comments beginning ‘You should have…….’ or ‘Why didn’t you……’ often offend even if they are not intended to!

Avoid post mortems at the end of every hand.  If you want to discuss a hand, wait until the end of the round if there is any time left.  Better still, if hand records are available, save post mortems with your partner until after the session.

Bidding Boxes

Most clubs now use bridge bidding boxes.  The bid cards must remain on the table until the opening lead is made, then they are put back in the box.

STOP CARD

Place the Stop Card on the table before you make any jump bid.  This includes any opening bids higher than the one level e.g. 2C, 3D etc.  Replace the Stop Card in the bidding box after making your bid.

ALERT CARD

When your partner makes any artificial or conventional bid you pull out the Alert Card and make sure that both opponents have seen it (then replace it).  ALL bids that do not have a natural meaning (i.e. normally showing 4 or more cards in the suit bid) should be alerted, these include:

Blackwood and responses

Gerber and responses

Stayman and the 2D response

Strong 2C opening bid and the 2D response

Fourth suit forcing

Cue Bids

Transfers (both bids)

BRIDGE SCORES

You can use the back of the cards in the bidding boxes to check the score:  GREEN scores are used when not vulnerable and RED when vulnerable.

Movements

MITCHELL MOVEMENT

The most common bridge movement you will encounter is the Mitchell movement.  In this movement all the North/Souths stay seated and the East/Wests move up one table.  Usually there are two winners, a North/South winner and an East/West winner.  Sometimes the director will ask for an Arrow Switch on the last round to enable there to be just one winner.

HOWELL MOVEMENT

When there is only a small number of tables (especially if there is a half table) the director may play a Howell movement.  In this movement almost all of the pairs move at the end of each round.  There will be a movement card on each table showing which table and which direction (N/S or E/W) each pair needs to move to at the end of the round. 

It also shows which pairs should be at the table for the current round and which boards should be played.  It is North's responsibility to check that the right pairs and the right boards at at the table (though it is a good idea for everyone to check).  If a pair play at the wrong table or the wrong boards are played this causes serious disruption!

A useful tip is to look at who is seated at the position you are going to move to next... you normally follow this same pair on each round.

Arrow Switching

Sometimes the director will ask for an Arrow Switch on the last round of a Mitchell movement to enable there to be just one winner.  (The correct number of boards to switch is one eighth of the total boards). 

It is often a mystery to players how arrow switching just a few boards makes the competition fair between all the North/Souths and East/Wests.   There is some interesting mathematics involved!

CONTROL OF A DUPLICATE SESSION

Starting, Playing rounds and Finishing

Please arrive promptly and in time for the director to plan the movements and number of boards to be played. Do arrive at 7pm for a 7.15pm start. For example there are completely different movements and total of boards when you are 7 ½ tables than when you are 7 tables. Thus if a pair turns up late or just on time and for example then makes 7 ½ tables, the boards and movements then have to be changed at the last minute by the director.

Make sure you know exactly what you pair number is and then enter your pair number correctly onto the identity slips. Make sure that you remember this number as you play each round. It is vital for the correct scoring. If you are moving, then give it to the pair as you first sit at their table. You may be asked to shuffle and deal the first set of boards on your table. If you are the first group to play the boards then the curtain cards will have to be filled in before you begin play. These show the hands for the North, South, East and West cards respectively. Please make sure these are always accurately filled in and are retained in their correct board position. The quality of the play will be damaged if for example the next West sees a curtain card marked with East’s hand while looking at the West cards.

There is normally an agreed stopping time, thus the Director has to manage each round so that the whole event can complete on time. It may be necessary to curtail any slow play by requiring the unfinished board on a table to be stopped and marked as “passed out”. This is in order to complete the round on time and thus avoid penalising all the other players if the final round is curtailed or abandoned.

When you have finished all the boards you may be asked to shuffle and deal the cards ready for their next use. If you are entering the final score on the traveller as North, quickly check the others scores look correct. The best chance of rectifying any errors is while other players are still there and may have their own record or still remember the hand and what was bid and with what result.

Computer Scoring, how it works.

The computer needs to be told exactly what the contract is and only that. If a contract is 3NT then that is the contract. It is not 3NT+2 even if 2 overtricks are made. The two overtricks are part of the play not part of the contract. A doubled contract is 3NT*. Doubling is part of the contract details not the play. Once the play is completed the computer needs to be told exactly how many tricks were made e.g. 11 tricks and not +2. The computer can work out the overtricks and the scoring from the two elements, the precise contract and the number of tricks made. Finally the computer needs to be told exactly whose contract it was. It must be told it was North; it cannot deduce this. If the contract is wrongly entered as East it will assume East did make 3NT even if all the other scores were for North. It then uses the pair numbers on the traveller in the North/South and East/West columns respectively to assign the result to somebody. It must be told correctly that is was for example for pair 4 N/S against pair 11 sitting E/W. If you enter your pair number the wrong way round on a traveller it will assume the contract for the wrong pair.

Once all the scoring is entered the computer will allot the same total points per board to each set of North/South’s and East/West’s that played it. For example for an eight pairs team event 12 points is allocated to each set of pairs per board. If you got a sole top you will get 6 points. If you share top you will get 5 points with the other pair. Likewise if you are sole bottom you will get 0 points, but a shared bottom gets 1 point each. If there were 21 boards played the maximum points you can score is 6x21 i.e. 126 points. If you got this it will give you 100%. If you scored 72 points you will get 72/126 as a percentage i.e. 57.1%. This is your overall score regardless of whether you are N/S or E/W.

Since both sides score the same and an arrow switch enables an effective  cross competition to occur between all the N/S and E/W pairs, the overall scoring can be ranked as a single cross table result. If for example in a half table competition someone played fewer boards than some of the other pairs the computer will still produce a correct overall %. Thus in the example above, if Jack and Jill played only 18 boards and scored 66 points their percentage is 66/(6x18) i.e. 61.1%. Thus they will beat you although you scored 72 points from the 21 games you played.

You might have deduced that the average score should be 50%. This is true. If you scored more than 50% you have done better than average regardless of your overall position. Likewise if you scored less than 50% you have done worse than average. On a 21 board competition, a sole top on a single board represents about 5% of your total score. Thus if the result is wrongly entered one pair will get 5% less on their total and one will get 5% more than they should have. This can be quite a big swing on a close score competition. It emphasises the need to write the key data down correctly on the sheets. This % scoring also means that your performance relative to the midpoint mark of 50% is valid regardless of how many boards are played or how many pairs compete. Thus from week to week you can compare your performance even though the number of tables, boards, movements and make up of the pairs can all vary.

MOST OF ALL ENJOY YOUR BRIDGE – IT SHOULD BE FUN