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When the U.S. air force discovered the flaw of averages

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Re: When the U.S. air force discovered the flaw of averages

#41
post #21

joint distribution of 2 normal distributions isn't necessarily a normal distribution in 2 variables. Independence would be sufficient condition for that, yet obviously there is no independence between various measurements of a human body. https://en.wikipedia.org/wiki/Multivariate_normal_distributi...

Which is funny, because the problem seems to arise exactly because the variables are independent. If they were dependent then one could imagine all sizes correlate with height, for example .

Re: When the U.S. air force discovered the flaw of averages

#43

Articles like this remind me how rational and practical the military is. I know so many brilliant military minds, yet war itself seems outdated and plagued by so many emotionally irrational decisions. I can't reconcile those two thoughts. How can people inside the military be so incredibly smart, yet still think it makes sense to ... you know, kill people's friends and families and not expect them to become terrorist…

"the average man" is a very 19th Century Determinist concept. There may also be other 19th century Determinist concepts lurking around in military doctrine.

Those are frequently the troublesome ones that don't fit actual measurement.

At least in the US, there was no standing army until the 20th Century.

Re: When the U.S. air force discovered the flaw of averages

#44

Wow! This has implications for human genetics (a study that originated partly in considering human body size measurements like those described in the article) that I think most popular writers on human genetics have not taken into account. There was an article posted to Hacker News earlier this week that suggested, surely falsely in my opinion, that human genomes can be optimized for intelligence to such a degree tha…

Similarly, imputation of "race" by genome testing depends crucially on assuming that the average genome is informative,

This is a nonsensical mischaracterization of both modern genetics and the theory of high dimensional vector spaces.

The phenomenon the article is discussing is the fact that the mass near the center of a normal distribution approaches zero as the number of dimensions goes up, and that most of the mass lives a distance sqrt(N) from the origin. This does not imply that a) you can't have gaussians or other distributions which are separated from each other or b) that projections of one of these distributions can't have a different distribution than a projection from the other.

Please go read Foundations of Data Science, chapters 1 and 2 before expounding on this topic further: http://research.microsoft.com/en-US/people/kannan/book-no-so...

Can you clearly state what, precisely, you think this article proves about either classification, intelligence augmentation or group differences in specific traits?

Re: When the U.S. air force discovered the flaw of averages

#45

Wow! This has implications for human genetics (a study that originated partly in considering human body size measurements like those described in the article) that I think most popular writers on human genetics have not taken into account. There was an article posted to Hacker News earlier this week that suggested, surely falsely in my opinion, that human genomes can be optimized for intelligence to such a degree tha…

This is old news for geneticists. Since Mendel and Punnet we've known that a.) traits don't average or "mix" from parent to child and b.) individual traits don't assort randomly.

In a more modern context, the Human HapMap project (http://hapmap.ncbi.nlm.nih.gov) is working on mapping out just how many different assorting groups exist among human genes.

Re: When the U.S. air force discovered the flaw of averages

#46
The thing that strikes me here is how much we repeat the mistake of Norma (taking the mythical average body and assuming that differences mean problems) today in talking about people's minds.

I started using computers before it was fashionable, before my fellow nerds started being worth billions and ending up on magazine covers. It's hard to describe now how much our difference was seen as wrong, as the sign of a problem.

I have to wonder how much other natural differences gets medicalized. I know I have friends who take drugs for "insomnia" even though the only problem they experience is that they don't always get the "average" night of eight hours uninterrupted sleep. (Which anyhow is a modern invention. [1]) When I was in mourning after my mom died, a few buttinskys suggested I talk to my doctor about antidepressants, even though actual experts thought I was doing fine. And I worry about the number of schoolkids who have their differences medicalized because, in effect, they are inconvenient for overburdened teachers using industrial-age models of education.

I have no solution here, but I definitely find it troubling.

[1] For more, see this podcast, especially the "Til Morning is Nigh" segment: http://backstoryradio.org/shows/on-the-clock-4/

Re: When the U.S. air force discovered the flaw of averages

#47
post #27

Earlier quoted context omitted.

Yeah, I was thinking of the same thing. It's not my field professionally though, so I am not sure what the relevant conclusion would be for machine learning though (or if the comparison holds at all).

I don't think that's quite correct. Recommendation engines normally work by taking the things you favor, then looking at who else favors those things, and deducting that you're all likely to have shared interests.

Yeah I'd assume the simplest recommendation engines work on correlation. A recommendation engine working on average would be complete garbage, you'd be better off picking recommendation at random.

Re: When the U.S. air force discovered the flaw of averages

#48

Wow! This has implications for human genetics (a study that originated partly in considering human body size measurements like those described in the article) that I think most popular writers on human genetics have not taken into account. There was an article posted to Hacker News earlier this week that suggested, surely falsely in my opinion, that human genomes can be optimized for intelligence to such a degree tha…

You might like this article:

http://blog.watsi.org/netflix-and-global-health/

Re: When the U.S. air force discovered the flaw of averages

#49
post #46

The thing that strikes me here is how much we repeat the mistake of Norma (taking the mythical average body and assuming that differences mean problems) today in talking about people's minds. I started using computers before it was fashionable, before my fellow nerds started being worth billions and ending up on magazine covers. It's hard to describe now how much our difference was seen as wrong, as the sign of a pro…

Modern psychology does not care about average it cares about capable of functioning in society. If you can't avoid say screaming in public that's a problem not just a non issue. Arguably the tolerances might be low, but it's hard to argue with the basic premise.

Granted doctors assume if your talking to them you have a problem. But that's arguably a reasonable prior.

PS: The extremes of behavior get very far out there, notmenjoying talking to people is fine, not being able to so communicate is an issue.

Re: When the U.S. air force discovered the flaw of averages

#50
post #34

Earlier quoted context omitted.

Why is it certainly false?

The simplest example I can come up with is the weight - the density of humans is probably constant for practical purposes and therefore the weight must be positively correlated with your body dimensions. It is also pretty obvious that humans, or tissue for the matter, does not grow in a strongly directional manner. If you gain weight more or less all dimensions not constraint by your skeleton will increase, i.e. you…

Sure, but weight gain in adulthood doesn't cause you to get taller.
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