Radlett U3A Duplicate Bridge Workshop€¦ · score doesn’t matter –if every NS bid and made 7NT you would get an average. If you bid and made 7NT but everyone else bid and made

Radlett U3A Duplicate Bridge

WorkshopGary Harding August 2018

Final V2.0

Agenda

• The deals and how they are prepared

• The movements I use

• How duplicate bridge is scored

• The impact of the scoring on how you should bid (and if possible play)

• What information is available on our BridgeWebs site and how you can use it (I will not be able to cover all of this but will at least give an introduction).

The deals and how they are prepared

• I currently use the Dealer4 Programme which deals random boards using the BigD programme (also used in international tournaments and many bridge clubs worldwide)

• This could be used to drive a Dealer4 card dealer but they are expensive (~£4,000)

• I use it to create ‘deal’ files in PBN format which I then send to someone who ‘deals’ the board for us (he uses either a Dealer4 or a Duplimate – a similar machine with a similar price!)

A Dealer4 machine

https://www.youtube.com/watch?v=i-vTLPKIxtw)

Dealer4 can also do double dummy analysis

What does it mean?

Movements

• Two basic types of movement, Howell and Mitchell

• Howell is best for up to 5 tables, all (or all but 1 pair) move tables either according to a table direction sheet or instructions on the tablet

• As we now almost always have more that 5 tables I use Mitchell movements

Mitchell Movements

• People and boards move so that most people play most (all) people sat in the opposite direction and also play most (all) boards one way or the other

• North – South remain stationary, E-W and boards move in opposite directions

• Simple for an odd number of tables, E-W up a table, boards down a table

• For an even number of table either need to ‘share and relay’, or skip a table in the middle of the session to avoid EW playing the same boards again

Advantages and disadvantages

• Howell

• + Can work for as few a 3 tables

• + For a small number of tables you get to play against all (or most of) the other pairs

• - no or few stationary positions

• - gets complicated and unbalanced if more than 5 tables

• Mitchell

• + Simple rules to follow

• + With Arrow Switch can get a whole field result

• - does not work with less than 5 tables

Arrow Switch

• With an ‘Arrow Switch’ one, or sometimes two, rounds are played with the boards in the opposite orientation, i.e. those players who had been playing the NS hands play the EW hands and vice versa

• If you don’t do an arrow switch the NS and EW pairs remain in separate sections so you would have a NS winner and a EW winner

• By doing the arrow switch the each pair gets compared with the opposite side on some boards and so you get a single result

• The mathematics of how this works is quite complicated but as a rule of thumb one board in eight should be switched so we normally just do it on one round out of the 8 or 9 we normally play

Basic Duplicate Play

• Each hand is scored similar to rubber bridge

• Dealer and Vulnerability is determined from the board

• No score for ‘honours’

• Hands are put back in the board at the end of each boards play

• After each round the boards are moved to a different table to be played by a different pair of players

• In a single session no pair plays the same board twice (in some circumstances two pairs may play each other twice ‘a revenge’ but with different boards)

Traveller

Bridgemate

BriAn

After play

Others results

Scoring

• At the end of the session we have the results from all boards played by all pairs something like this:

N/S E/W Bid By Tks N/S E/W

1 16 3♠ S 8 100

2 10 1NT N 7 90

6 9 2♥ S 5 300

7 12 2♣ N 9 110

8 14 2♠ N 9 140

15 5 3NT N 6 300

Scoring

This is then sorted into order (in this case worst

to best for NS):

N/S E/W Bid By Tks N/S E/W

6 9 2♥ S 5 300

15 5 3NT N 6 300

1 16 3♠ S 8 100

2 10 1NT N 7 90

7 12 2♣ N 9 110

8 14 2♠ N 9 140

Pairs Contract Scores

Scoring

Match points (MPs) are give to NS according to

the formula(0 to (number of times

played -2) times 2)

N/S E/W Bid By Tks N/S E/W N/S E/W

6 9 2♥ S 5 300 0 9

15 5 3NT N 6 300 2 9

1 16 3♠ S 8 100 4 6

2 10 1NT N 7 90 6 4

7 12 2♣ N 9 110 8 2

8 14 2♠ N 9 140 10 0

Pairs Contract Scores Points

Scoring

• Where there is a tie each pair in the tie gets the average of the MPs

N/S E/W Bid By Tks N/S E/W N/S E/W

6 9 2♥ S 5 300 1 9

15 5 3NT N 6 300 1 9

1 16 3♠ S 8 100 4 6

2 10 1NT N 7 90 6 4

7 12 2♣ N 9 110 8 2

8 14 2♠ N 9 140 10 0

Pairs Contract Scores Points

ScoringEW get the top score (in this case 10) less the NS score

N/S E/W Bid By Tks N/S E/W N/S E/W

6 9 2♥ S 5 300 1 9

15 5 3NT N 6 300 1 9

1 16 3♠ S 8 100 4 6

2 10 1NT N 7 90 6 4

7 12 2♣ N 9 110 8 2

8 14 2♠ N 9 140 10 0

Pairs Contract Scores Points

Real example(Board 2 – 13th October 2016)

• Sorted

N/S E/W Bid By Tks N/S E/W N/S E/W

1 9 2NT S 7 100 0 10

7 13 2♦ E 7 50 2 8

14 4 1♥ N 7 80 4 6

8 15 2♣ N 9 110 6 4

6 11 2NT N 8 120 8 2

5 16 4♣ S 10 130 10 0

Pairs Contract Scores Points

Board No 2 N/S Vul Dealer East

A correction might be made

• If some boards are played more than others (e.g. due to skips or relays) a Neuburg correction is made so that they are close to equivalent).

• E.g. if some boards are played 6 times the top is 10 and some boards are played 7 times the top Is 12 it is unfair on the pairs that played the boards that were played less times. An adjustment is made which would turn the top on the boards that are played 6 times to about 11.8 (exact number is dependent on a number of factors!).

All of the MPs are added up for each pair

Correction for number of ‘tops’• If some pairs have played more

boards than others (e.g. due to a sit out) absolute number of MPs would not be fair.

• So the MPs scored is divided by the maximum number of MPs available to that pair to give a %

• This is then used for the rankings!

How and why scoring can impact what you should bid

• The absolute score you get on a hand is not important – it is how much you have scored compared to the other people playing the hand in the same direction

• Note the arrow switch means that you also get compared against some people who played most boards in the opposite direction

• The absolute number of points you score doesn’t matter – if every NS bid and made 7NT you would get an average. If you bid and made 7NT but everyone else bid and made 7 Spades you would get a top!

• Major suit fits tend to be better than minor suit fits, e.g. 3C+1 scores 130 but 2S+1 scores 140 – giving you a better result

How and why scoring can impact what you should bid

• It can be better to go down (get a negative score) than let opponents make a contract

• E.g. 2S for NS scores -110 for EW, 3C-1 scores -50, even -2 is only -100 so both a better result

• Check vulnerability as that can make a big difference, particularly if doubled but can still be good against game and slam contracts

• Going down -2 vulnerable is -200, the opponents would have to be +4 for the -2 to be better

How and why scoring can impact what you should bid

• If one side is in game or a slam even bigger losses (a sacrifice) can give you a good result

• E.g. Both NV, 4S by NS is -420 for EW, 5C could go -8 if not doubled for -400, a better score, if doubled only -2

• With favourable vulnerability (e.gNS vul, EW non-vul) could be -3 and doubled for a better score -6S vulnerable making is 1430 points, 7Cx non-vulnerable -6 is 1400

• Adverse vulnerability makes a big difference - 6S non vulnerable making is 980, 7Cx vulnerable -3 is 800

How and why scoring can impact what you should bid

• A long suit or good shape suggests a sacrifice could be good

• As a rule of thumb if you think a game or slam has a better than 50% to 60% chance of making you should bid it – there will be other opponents at the other tables who will do it and if you miss out you will get a low score or bottom

• Equally if it doesn’t make then you are better to stay low and get a +ve part (or game) score while your opponents at other tables get a -ve result

What to think about when playing a contract in duplicate

• If you in a good contract that no one else, or at least very few, will be in - try to make the hand at all costs. You can even indulge in taking a safety play (conceding a trick to guard against bad splits). Especially true if you are doubled or in a slam.

• You are in a bad contract. Let's say you are playing in 3 No Trump while you suspect everyone else will be in 4S. E.g. look at Dummy: a 5 card Spade suit opposite 4 Spades in your hand and 3 losers. Pairs playing this hand will score 420 points in 4S while your 3 No Trump contract will score 400 points for a bottom or near bottom. You must make the over trick at all costs and score 430. You must even risk making the contract for the sake of the over trick. In this case minus 50 is the same as plus 400; both a terrible Match Point score

What to think about when defending a contract in duplicate

• Do you go all out and try to defeat the contract; or focus on restricting the Declarer 's overtricks. The bid and the cards determine the answer.

• If the Declarer in an excellent contract that no one else in the room will be in, then the strategy is to try to defeat the contract at all cost; do not worry about overtricks.

• The Declarer seems to be in the right contract; that is everyone in the room will be there. Now the defence has to restrict the declarer from making overtricks. That is keep the overtricks to a minimum.

• Even if you cannot defeat the contract make sure get all the possible tricks –take your winners

A slam might only be worth 2 pts more than game! (Board 3 – 13th October 2016)

N/S E/W Bid By Tks N/S E/W N/S E/W

1 9 3NT S 8 50 1 9

7 13 3NT S 8 50 1 9

6 11 5♦ N 11 400 4 6

8 15 3NT N 11 460 6 4

14 4 3NT N 12 490 8 2

5 16 6♦ N 12 920 10 0

Board No 3 E/W Vul Dealer South

Pairs Contract Scores Points

How going off can give you a top!(Board 11 - 22nd September 2016)

N/S E/W Bid By Tks N/S E/W N/S E/W

6 15 3♥ E 8 50 0 14

17 7 3♥ E 7 100 2 12

5 13 2♦ N 9 110 5 9

8 10 2♦ N 9 110 5 9

1 14 3♦ N 10 130 10 4

2 16 3♦ N 10 130 10 4

4 11 2♦ N 10 130 10 4

3 18 4♥ E 6 200 14 0

Board No 11 None Vul Dealer South

Pairs Contract Scores Points

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analysis

Final scores by all pairs and MPs

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Questions?