[monikrazy]

Interesting concept for a study.

Unfortunately, the way the study defines risk isn't accurate: "Our general assumption is that the higher the winning contract the greater the risk of failure."

Risk would be better defined by the chance a partnership fails to maximize its score with a given set of actions.

[barmar]

monikrazy, on 2014-January-27, 13:08, said:

Interesting concept for a study.

Unfortunately, the way the study defines risk isn't accurate: "Our general assumption is that the higher the winning contract the greater the risk of failure."

Risk would be better defined by the chance a partnership fails to maximize its score with a given set of actions.

Risk should be defined relative to the information that has been exchanged during the auction.

Making a major or NT game usually requires about 25 combined points (HCP + distribution). If the auction has only shown that the partnership has at least 20 points, and they bid game anyway, they're taking a big risk. But if it has shown at least 28 points, then making game is very likely, and NOT bidding game is taking a big risk.

[barmar]

Also, risk can be taken during the auction. If you invite game when you only have a minimum, you're taking a risk that partner has nothing extra and you'll get too high. Conversely, if you have extras and fail to invite, you're risking missing a game if partner has a hand that would accept the game try.

[Vampyr]

Sorry barmar, deleted the post you replied to because I thought it didn't add much to what Zel's said above.

[barmar]

Vampyr, on 2014-January-27, 17:09, said:

Is 7♥ harder to make than 1 ♦? Well, there are thousands of hand combinations that can make the former but not the latter.

True, but effectively irrelevant. No competent players, with hands that can make the former, is going to bid the latter, no matter how risk-averse they are. So you can ignore that possibiilty.

The 3NT versus 4/5minor example is more on point.

These are all just variations on the theme I described: You have to compare what they did bid against what they should bid given the information they have.

[Vampyr]

barmar, on 2014-January-27, 17:15, said:

True, but effectively irrelevant. No competent players, with hands that can make the former, is going to bid the latter, no matter how risk-averse they are. So you can ignore that possibiilty.

Yes, but players can easily end up in the wrong contract that is levels lower than another contract that is easy. Down in 3NT with six of a minor cold? We've all been there. This may involve some combination of system and risk-taking in the auction, but serves more as an example of how this numerical scale does not correlate very accurately with the chances of a contract succeeding. (Also, I have never noticed a 2♠ contract playing 3 points worse than 2♣, or 3 points better than 3♦. Any attempt at quantification of contracts has to take the level of the contract into consideration. Obviously.)

As far as what they should bid and what information they had, this of course would require a careful analysis of each auction and an expert knowledge of the bidding systems in use.

[Vampyr]

monikrazy, on 2014-January-27, 13:08, said:

Interesting concept for a study.

Unfortunately, the way the study defines risk isn't accurate: "Our general assumption is that the higher the winning contract the greater the risk of failure."

Risk would be better defined by the chance a partnership fails to maximize its score with a given set of actions.

This is a good point. And it brings out the fact that players who choose to defend are left out of the data.

[barmar]

Vampyr, on 2014-January-27, 17:25, said:

As far as what they should bid and what information they had, this of course would require a careful analysis of each auction and an expert knowledge of the bidding systems in use.

True. However, the nice thing about duplicate bridge is that there's plenty of other information that can be used as a substitute for a detailed analysis of the auction.

Without having a simulation, you can approximate this simply by comparing players with the field. Players who land in contracts different from most of the field are probably taking a risk, because everyone has about the same ability to share information, and the field is usually right. This doesn't hold true for every hand, because some systems are better suited for some hands than others, or the opponents may have interfered differently. But over the long term, these differences should even out.

This is similar to the way my financial advisor is able to tell me that my portfolio is making more money with less risk than the S&P 500, simply by calculating each portfolio's "beta" over a period of time-- he doesn't have to analyze every investment decision we've made.

[Zelandakh]

barmar, on 2014-January-27, 18:42, said:

This is similar to the way my financial advisor is able to tell me that my portfolio is making more money with less risk than the S&P 500

Is he taking fund management costs into account for this calculation? Costs for tracker funds are typically much lower than actively managed ones and most independent analyses of this have concluded that low cost tracker funds outperform actively managed funds over time once these costs have been factored in.

[barmar]

Zelandakh, on 2014-January-28, 04:23, said:

Is he taking fund management costs into account for this calculation? Costs for tracker funds are typically much lower than actively managed ones and most independent analyses of this have concluded that low cost tracker funds outperform actively managed funds over time once these costs have been factored in.

I believe he's using total return, which takes management expenses into account, and comparing it against the unmanaged index (no fees at all there). I'm not sure if he's taking the wrap fees that Ameriprise charges for the his services into account, though.