# Are there times to double for a one trick set in duplicate, when you would not do so in rubber?

In rubber bridge, I would "never" double a part score contract for a one trick set. The reason is that a successful double will increase your score from 50 to 100 if the opponents are not vulnerable, and from 100 to 200 if vulnerable, that is produce a gain of 50-100 points. On the other hand, doubling opponents into game will add a 500 to 700 game bonus to their score, plus 50 in penalties, and double the value of their original part score contract if they make it. The "skewness" of the two possible outcomes argues strongly against a "hair trigger" double.

In match points, a successful double of a part score will increase the penalty from 100 to 200 when opponents are vulnerable, likely enough for a "top" if this is truly a part score battle. It will be a "bottom" relative to other part scores if it fails. But at least the results are "symmetric."

Given the difference between "skewed" and "symmetric" results, are there situations in matchpoints where one would double for a one trick set when one would not do so in rubber?

Absolutely! It's a key strategic ploy in competitive auctions.

The key factors that I have always made the decision on is if all of the following conditions are true:

1. Opponents are Vulnerable, so the one trick set is worth 200 Points. The maneuver is a risky one, and can only be justified if the gain is near certain to get one a top in exchange for the certain Bottom being risked.

2. We have no further competitive actions available at the Two Level. Attempting to score 110 in a Major, or 120 in NT, has a better risk-benefit trade-off as long as it is available. This usually, though not always, means the Double is made of a Three Level bid.

3. There is good reason to infer that getting the Undoubled 1-trick set is not just a bad board, but a very bad or bottom board. Worse than 2 out of 12. Converting a passel of 2's and 3's into 0's will ruin a game, so avoid that nonsense.

4. From the bidding, one knows both where the setting trick is coming from and how the Defense should go. No nonsense making this double and then huddling over Opening Lead - if you don't know what to lead, and how to follow up, this Double is out of place.

Remember that a plus score, especially in a competitive auction, is rarely a Bottom. The key to successful Duplicate Bridge is avoiding the Bottoms - as the Opponents will always throw a Top or two your way. If you can average 7 (or even 6.5) Match Points over 24 or 25 Boards, and then throw in a gift top or two that weren't gifted back, that's a session score of 176 to 182 on a 156 average. That's a successful game.

The key risk with tight Doubles (as with all attempts to create action in the Bidding) is the lack of detailed information. One can more reliably create good scores in the Play, whether as Declarer or Defender. Throwing away a hard-earned overtrick or undertrick on an over-confident speculative Double is not successful Bridge.

Finally, I have known very successful players who occasionally make this for a not Vulnerable set. It's part of their success. But on those occasions when I've been playing up, not once has the remark been made that "I" should have made such a call. I'm looked for and at as a reliable, if not quite regular, partner because I will bid steadily and reliably; find a few extra undertricks and overtricks in the play; and give nothing back unforced.

Update

Reading the comments, there seems to be a presumption that your only option is to Pass or Double.

1. That's not true. Learn to balance if the Opponents are buying more than 1 hand per session in 1NT, and burying you with them; that's just absurd. Those are your hands. Why aren't you in the auction? Play old-fashioned ASTRO promising a 4-card Major and a longer lower suit if need be. Setting 1NT is hard - harder than making 7 tricks in a 2-level contract of your denomination - so get into the auction.

2. There will be anywhere from 3 (Good day. Yeah!) to 6 (Bad day. Boo!) where the Opponents are in control. The goal on these hands is to: (1) Identify them; and (2) Get out with an Average Minus. These are not the hands to try for Top or Bottom on; these are the hands to play steady on. Some days you're simply not dealt a possible 200 score.

• So it's "never" in rubber and only "rarely" in match points. Under restrictive circumstances: 1) opponents are "sacrificing" by bidding e.g 3 minor over 2 major. 2) You know where the setting trick is 3) Without converting a vulnerable -100 to -200, you are almost as likely to get a bottom or near-bottom as if you tried and failed. Therefore try and (hopefully) succeed. – Tom Au Jan 25 at 17:39
• @TomAu: There will always be part-score hands, every session, where the Opponents are entitled to earn an 8 or 9 if they bid and play correctly. Turning your 3's and 4's into 0's is losing bridge - unless you're getting nearly as many 11's; and those 11's are harder to come by than you realize. Often one pair in the room had a meltdown and gave up 500, so the best you're ever getting is actually a 10, tied with two other pairs. Sometimes you key Declarer's play and turn +100 into -750. Perhaps everyone's down and +100 is a near top. Not every hand is yours - accept it. – Forget I was ever here Jan 25 at 18:07
• The point I was trying to make was that this is at least "permissible" in matchpoints, but "rare" even then .I wasn't thinking every hand, or even every other or third hand. Maybe every eighth or tenth. But those "eighths" or "tenths" add up to two or three hands a session. The other thing I got from your comment is that you wouldn't double if you thought you could get 2 points out of 12 by not doubling. That would imply that you are only "risking" 1's or 0's against "top or bottom, which would have a weighted average value of 4-6 out of 12. – Tom Au Jan 25 at 18:36
• @TomAu: Half that - once per session is more typical. There will always be 3 to 6 hands per session where Opponents - not you and Partner - have control in the Bidding. Attempting to control those hands is how you end up with a 35% game. Let them go, and try to get the extra trick in the play to salvage Average-Minus. If there's 6 such this session, it's just not fated to be a brilliant session. Play solid; go home with your 170 or 175; and look forward to the 'morrow. A session where Opponents are in control only thrice will come by; and that's the session to try for 200. – Forget I was ever here Jan 25 at 19:39
• I think this is right, for the most part, at the club level. I don't think that you can assume, for example, that `a plus score, especially in a competitive auction, is rarely a Bottom` in the higher levels of competitive Bridge; plenty of times there you'll see auctions where 25/30 hands are 1N= +90, and your opponents happen to play an odd 1N system that happens to end up in them declaring 1N instead, for -1. You double (+100=good board) or you don't (+50=bad board). In club bridge you just don't have that kind of consistency, so reliable positive is more important.. – Joe Jan 25 at 19:50

In very competitive bridge, awareness of when you can double is essential. When it occurs is most often in match points - not IMPs, where the risks and rewards are more similar to Rubber - and in very specific situations. But from my experience, midlevel players don't double nearly as often as they should; perhaps for the best in some cases as they don't have the experience to recognize the situation (and I'd count myself in that group for the most part nowadays), but still - they cost themselves not doubling when they should.

In particular, at the higher levels, you should be able to tell what the rest of the room likely is in. This often occurs when you're facing opponents with unusual conventions, or aggressive opponents. Say, you're in a clearly comfortable spade partscore (2H, expecting to make 8 tricks comfortably, but not comfortable with the game or even the 3 level), after a slowly developing uncontested auction. Your LHO doubles 2H for takeout, and RHO bids 2S. (Yes, this is not that uncommon in aggressive play - the "late" takeout.) This is all vulnerable.

You've clearly got 110 to 140, maybe, and they all of a sudden are declaring, and you're looking at probably setting them 1 - the "cost" in switching from hearts to spades (and switching to defense) is around 2 tricks, in this case. If you pass, they go down one, and get a top board - that's the point of the interference. You have to recognize to double here - because of your situational awareness, that the late takeout double will be fairly rare, and most everyone else will be 2H= or 2H+1, and if you are setting 2S 1, you're bottom board! You could bid 3H of course, but that has its own risks - and if your hand evaluates as perfectly fine on defense, given the point advantage (say you think it's about 22-18), you want to double.

That situational awareness of course also has to recognize when it's a bad idea - when they're not bidding speculatively, but just slowly.

Gavin Wolpert has a good piece on this; in that, he notes first:

When we are entitled to +140 and the opponents compete, scoring +100 just won't cut it. The risk of doubling depends on how many tables have competed to the same level. If we judge that most pairs will sell out and let our counterparts holding our cards make 140, then we must try to protect our equity by getting a bigger plus score.

But then, he shows the opposite:

To demonstrate let's change gears and look at what happens when your opponents bid one more over your 5 level sacrifice. Since most of the field will either play in 4 or double the sacrifice, you will most likely get a near top for +50. If you double them you effectively give up your edge. A plus score of any kind will win the board against all tables which do not find the sacrifice. You will also win the board against all the tables which stop and double the sacrifice. The extra penalty for the double does not help you.

Here the X is tempting, but unnecessary - you already have your advantage over opponents (forcing them to try and make 5); doubling is silly, even if you do think they'll make.

The point is recognizing when it is necessary to protect your part score. When it is - when you have a solid > 100 points in the bag, and they interfere - you basically have a bottom board anyway if they make, or go down one undoubled, so you have to double. It's just a matter of experience recognizing those versus the times when it's just a competitive auction and they happen to get in a bit late.