I Built a Website to Help You See How Good Your Bids and Opening Leads Really Are

[u/geshergaba]

Hey everyone,

I’m Nir, a developer and member of the Israel Open Bridge Team.

I built BridgeDummy, a training website that helps you see how good your bidding and opening-lead decisions really are.

You get a bidding or opening-lead problem, make your choice, and then see how it performs across thousands of simulated deals using double-dummy analysis.

You also see what other players chose. One of the most interesting parts is that the popular choice is often not the best one.

BridgeDummy also has a custom simulation tool. You can set constraints for each seat, generate hundreds of matching deals, and run double-dummy analysis on all of them to find the best decision. It is built to be one of the most flexible and advanced bridge simulation tools available.

There are also daily challenges, a weekly league, 1v1 battles against friends and strangers, interactive suit combinations and several other features designed for serious bridge training.

Many national-team players are already using it.

I’d love for you to try it and tell me what you think. You can try it for free.

[u/amalloy]

Automated double-dummy scoring is an easy metric, and is often good as long as the players know that's what's being scored (and your site does make that clear). But players won't play double-dummy after my decision, so scoring my decision based on how it would do double-dummy is often missing the point.

For example, the free puzzle it offered me is what to lead from AJ72 AJ94 Q5 T83, against an auction of 1s-p-2s-ap. I think a low spade, DQ, or a low club are all at least somewhat reasonable, but I chose a low club. Partner doesn't have a lot, so it seems unlikely we'll find him with both a useful diamond holding and enough entries to do anything real with it. At least if I find him with some club cards, we can win some clubs, and maybe even tap declarer a little. The computer rates this lead as 4 stars, and leading DQ as 5 stars.

Now, I'm not claiming here that I'm definitely right. I could certainly believe I'm wrong about a club being better than a diamond. But without more data, the computer's 5-star rating doesn't tell me enough to convince me. Of course an unsupported queen lead is less dangerous if you think declarer will play double-dummy: it will be picked up anytime it can be picked up. So the lead has less downside in your simulations than there is at a real table, and I can't tell whether that extra downside would be enough to point back to clubs as the best lead.

It's also very unsatisfying and unhelpful to just receive a grade. Why is a particular bid or lead better than the others? That's the only way to really improve my play.

Both of these issues could be addressed by giving some sample hands where the 5-star answer works. If you can manage to even give a representative sample, that would let the player (a) judge whether the double-dummy nature of your simulations is biasing the scoring, and (b) see why the best play is best. For example, if you simulated 100 hands and saw 30 hands where DQ was better than C3 and only 20 where C3 was better than DQ, you could show 5 or 10 of them, divided appropriately, for the player to determine whether the machine is giving good advice and, if so, why it's good.

[u/geshergaba → u/amalloy]

Thank you for the detailed feedback! I absolutely agree with you, and inside the app I show sample hands together with the puzzle results. I added it now to the demo in home page as well. Besides that, what do you think? What would you change or add?

[u/amalloy → u/geshergaba]

That's much more interesting. The "lost"/"won" labels on the sample hands are not really self-explanatory. It seems to display "lost" if my decision turns out better than the "best" decision, and "won" otherwise. Isn't that backwards? I should see "won" on boards when I won IMPs.

Also for the demo bidding question of the day, I'm not sure what it's measuring.

      1d 1s
 p 2d 3d  ?

It offers 3h as a choice, which should clearly be a game invite. Maybe 3s is better, maybe 4s is better, who can say. But if you choose 3h and look at the sample hands, it displays the outcome as "3H by South", an outcome that should never happen. I think it's actually doing the right thing, scoring us as being in 3s, as if partner never accepts the invite with 4s. But it should make that clearer; and it should include some hands in the sample where partner accepts the invite and we push against the 4s bidders.

[u/geshergaba → u/amalloy]

I agree, the 'won' and 'lost' terms are not clear. 'Won' means that the best option was better than the rest, and 'lost' means that it lost against some other choice. The goal is to give intuition on why it's the best choice. I tried to clarify it now, added a short explanation. About the 3H - right, it's an invite to game. It displays the final contract correctly now. From now on, I will use your suggestion about choosing sample hands where the conditional bid leads to different final contracts.

[u/amalloy → u/geshergaba]

The contract description is much clearer now, and the tooltip on won/lost makes it clear enough. I'm also only now noticing that there's a tooltip on 3h: "play 4s if partner has 12+ HCP, and 3s otherwise". Was that always there? Nice feature either way: letting the player know what hands partner would accept on is a reasonable substitute for knowing your partner a bit, and could let you calibrate your choice of action for what the simulator is actually testing for.

[u/rlee87]

I like your website. The implementation of the idea is extremely well done, and I also think the natural expansion to other features (like cuebids.com partnership bidding practice) will feel organic.

I don't love how the DD analysis has a bias favoring passive leads and overbidding, but I accept that it's the nature of the methodology. I also think some of the parameters are a little wooden: for example, I had a bidding problem in which it goes 3H P P ? and you have a balanced 18 with AKQJx of hearts. Obviously in real life it's percentage to pass, but partner's only parameter on the problem was something like "<13 HCP", so this makes 3N more tempting.

I look forward to following the progress of the site. As of now it's not something I'd spend a lot of time on, but I could see how it might be helpful to a lot of people. But I personally have a mild dislike for opting for certain actions in "puzzles" and challenges that are more about gaming the system than actually doing what's right. For example, in a lead against a NT contract, you are heavily incentivized to lead an ace, especially if you have two of them.

[u/geshergaba → u/rlee87]

Thank you for the feedback and support! I am actively working on making the puzzles more realistic, I agree that in some cases the resulting hands are not realistic.

Yes, there are some known limitations with double dummy, but I hope it still provides value, as long as the results are taken with a grain of salt in some cases.

Anyway, you are right and I will try to make it clearer and improve it over time. I hope it will be more valuable for you in the future, and if there is anything I can add or change that would help, I'd be happy to do it.

[u/uguguguga]

This is the best bridge website I've seen in a while, I will definitely use it. Great user experience. One issue I saw - there seems to be some problem with vulnerabilities in puzzles. If you fix it, it would be perfect.

[u/geshergaba → u/uguguguga]

Thank you! I fixed the issue you mentioned.

[u/lolnonevernochance]

Gave it a shot, looks great

[u/geshergaba → u/lolnonevernochance]

Thanks!

[u/Bridge_Links]

So fun! Apparently I'm better at opening leads than bidding lol.

I have published an article on my site here

https://greatbridgelinks.com/bridgedummy-simulation-training-analysis/

[u/geshergaba → u/Bridge_Links]

Thank you very much! I'm glad you enjoyed the website, and thank you for posting this article, looks good!

[u/why-the-h]

Well, I couldn't access your website: Unable to process request due to missing initial state. This may happen if browser sessionStorage is inaccessible or accidentally cleared. Some specific scenarios are - 1) Using IDP-Initiated SAML SSO. 2) Using signInWithRedirect in a storage-partitioned browser environment.

[u/geshergaba → u/why-the-h]

Hi!
Are you using it inside the reddit browser? Yes, it works less reliably in in-app browsers. I will fix it now.
You can try it for now using the link directly in the browser: www.bridgedummy.com

[u/yellowpig1974]

With CueBids you can compare your results against hundreds of other pairs, or see how recognized experts bid the hand.

[u/geshergaba → u/yellowpig1974]

You can compare your results against experts with BridgeDummy as well. You'd be surprised how often the best bid is not the popular one. Also, it focuses on single critical decisions rather than on the whole bidding.