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How vulnerability affects bidding decisions

In this lesson we look at how vulnerability affects bidding decisions.

Vulnerability in bridge

In duplicate bridge, if you bid and make a game, you're probably going to get a good score. If you bid and go down on your game, you're probably not going to get a good score. The vulnerability as far as bidding game is concerned doesn't make as much difference as we might imagine.

Duplicate scoring making game

Let's imagine this is a duplicate score sheet.

So far two pairs are in 3♠, making three for a score of 140 and two pairs are in 3♠ making four for a score of 170. So game is close, touch and go.

Here's us, pair five, in 4♠ is making four.

Woohoo! And we are vulnerable. So the score is 620.

Let's calculate the match points.

620 beats all the other scores. So we win eight match points out of eight for a score of 100%.

What happens if we are not vulnerable?

Not vulnerable, 4♠ making four is 420. We still beat all the other pairs. And so we still score eight match points out of eight for a score of 100%. So we're not actually getting a higher percentage bidding our vulnerable game, we're getting a high percentage because we bid game.

Game going down

What happens if we go down?

I've calculated the scores this time for 4♠ by South down one, vulnerable. East West get a hundred points. East West getting a hundred is the same as north South getting minus 100. Our match points are zero. We beat nobody and our percent score is 0%.

Well, we were vulnerable. Perhaps it wouldn't be so bad if we were not vulnerable. Let's take a look.

4♠ down, one not vulnerable. Well, good news is we only lose 50 points. The bad news is it's still a bottom board and we get zero match points and 0%. So again, the vulnerability didn't actually make any difference.

Going down in a part score

I played this in 2, down 1.

Bridge Card Game

Notice that East and West can make 1NT. We can take five heart tricks and one diamond. So we would get six tricks, but then West would win the remaining seven tricks. Let's have a look at the score sheet.

We can see at every other table East and West made 1NT for a score of 90. And I forgot to mention we were vulnerable. So with my two hearts, by south down one we lose a hundred points. Vulnerable. That's the worst score because 100 to east west is the same as minus a hundred to north south. And all these nineties to east west are the same as minus 90 to north south. So minus a hundred is worse than all those minus nineties. And we score 0%.

Oh no, no, hang on. This was board 1. I forgot we weren't vulnerable. So another look.

2 by South, down one not vulnerable, is 50 points to east west. So minus 50 to North South, and that minus 50 is better than the minus 90 that the other north south pairs scored. We get a top score, 100%.

Vulnerability in part score matters a lot!

In the part score battle when both sides are bidding and the points are reasonably evenly split vulnerability makes a big difference. Ttwo down vulnerable is awful. If you're not vulnerable, then you can be a little more frisky because one down -50 or two down -100 can still be a good score.

tags: #scoring

Vulnerable or not, I hope you're enjoying your bridge.

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