Monthly Archives: August 2009

Reliability Theory

Happy families are all alike; every unhappy family is unhappy in its own way. First line of Leo Tolstoy’s novel Anna Karenina.

Broken cars vary more in their capabilities than fixed cars.  Fixed cars all have working engines, brakes, doors, radios, roofs, etc., but in broken cars some of these capacities are greatly diminished.   Broken vs. fixed houses, televisions, plumbing systems, and so on are similar.

Biological bodies, on the other hand, become less varied in their capabilities as they break down.   For example, with increased age the contributions of other factors like social status to human mortality rates becomes weaker.   Similarly high intelligence people vary more in their different mental capabilities.

What determines whether it is the more capable or the less capable systems whose capabilities vary more?  The following figure illustrates a general theory of broken systems (formally “reliability theory“): Continue reading "Reliability Theory" »

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Our Nutrition Ignorance

The June Skeptical Inquirer reviews what little we know about nutrition:

Nutrition research and practice have lagged behind many other biological and medical fields. … The data clearly show that much current advice about dietary pyramids, food supplements, megavitamins, and weight loss regimens is frequently unproven, erroneous, or even harmful and is often based on pseudoscience or derivative incorrect professorial opinion. …

Table 1. Examples of Essential Substances for which Recommended Daily Allowances are Known
1. “Calories” for fuel from carbohydrate, fat and/or protien
2. Vitamins (water- and fat-soluable)
3. Minerals (e.g., potassium, magnesium, calcium, zinc, salt, trace metals)
4. Essential amino acids
5. Essential fatty acids
6. High-quality protein (animal or vegetable, e.g., amaranth) ….

A healthy person (given RDA intake of the substances in Table 1) can proceed with a normal (see below), stable weight by eating predominantly fat or carbohydrates or protein or various combinations of these because of the body’s ability to interconvert and utilize carbohydrates, fats, and proteins (amino acids) as needed.  In other words, fat, carbohydrate, or protein can serve as the principal source of calories. …

In healthy people who ingest the essential nutrients in Table 1 and have a normal stable weight (BMI approximately 20-25), there is no convincing comparative outcome evidence (as I defined above) that common foodstuffs, e.g., saturated fats like butter, rapidly absorbed carbohydrates like white rice and potatoes, or animal proteins, are especially helpful or harmful. The notion that some diets (e.g., low-fat or low-carbohydrate) are better than others is not based on sound science. …

There is no rigorous scientific evidence for the utility of dietary supplements, including megavitamins in normal-weight (nonpregnant) adults with a stable BMI of 20-25 eating a diet containing adequate amounts of the nutrients in Table 1.

Hat tip to Robert Wiblin.

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Cash Shy

On Monday I did an interview for a TV show (to appear in 2010), and they put me up at a famous expensive hotel.  I’m sure others get extra value from this hotel, but it didn’t do much for me.  I asked the show manager about this and he said that they have ethical problems with paying cash to interviewees, but want to compensate them for their trouble.  I sighed, thinking: what exactly could go wrong with cash that couldn’t go wrong with generous travel compensation?

I suppose we could make sense of this by assuming that observers can’t be bothered to notice the amount of cash given or the quality of the travel provided, all they can tell is if you were given cash, travel expenses, or both.  But I’m kinda skeptical this is really what’s going on.

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Today I’m 50

Today is my 50th birthday.  I’m very glad to be part of a species that lives so long, and it appears that I should thank other lusty old men, and especially the fertile young women who find them attractive.  The details:

Evolutionary theory predicts that senescence, a decline in survival rates with age, is the consequence of stronger selection on alleles that affect fertility or mortality earlier rather than later in life. Hamilton quantified this argument by showing that a rare mutation reducing survival is opposed by a selective force that declines with age over reproductive life. He used a female-only demographic model, predicting that female menopause at age ca. 50 yrs should be followed by a sharp increase in mortality, a ‘‘wall of death.’’ Human lives obviously do not display such a wall. Explanations of the evolution of lifespan beyond the age of female menopause have proven difficult to describe as explicit genetic models.

Here we argue that the inclusion of males and mating patterns extends Hamilton’s theory and predicts the pattern of human senescence. We analyze a general two-sex model to show that selection favors survival for as long as men reproduce. Male fertility can only result from matings with fertile females, and we present a range of data showing that males much older than 50 yrs have substantial realized fertility through matings with younger females, a pattern that was likely typical among early humans. Thus old-age male fertility provides a selective force against autosomal deleterious mutations at ages far past female menopause with no sharp upper age limit, eliminating the wall of death.

So from old men everywhere to young women everywhere: Thank you thank you!

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Why Does Pharma Study Placebos?

As head of Lilly’s early-stage psychiatric drug development in the late ’90s, Potter saw that … the company’s next-generation antidepressants were faring badly, too, doing no better than placebo in seven out of 10 trials. … Potter discovered, however, that geographic location alone could determine whether a drug bested placebo or crossed the futility boundary. By the late ’90s, for example, the classic antianxiety drug diazepam (also known as Valium) was still beating placebo in France and Belgium. But when the drug was tested in the US, it was likely to fail. Conversely, Prozac performed better in America than it did in western Europe and South Africa. It was an unsettling prospect: FDA approval could hinge on where the company chose to conduct a trial. …

AsPotter and his colleagues [also] discovered that ratings by trial observers varied significantly from one testing site to another. It was like finding out that the judges in a tight race each had a different idea about the placement of the finish line. … The placebo response is highly sensitive to cultural differences. Anthropologist Daniel Moerman found that Germans are high placebo reactors in trials of ulcer drugs but low in trials of drugs for hypertension—an undertreated condition in Germany, where many people pop pills for herzinsuffizienz, or low blood pressure. Moreover, a pill’s shape, size, branding, and price all influence its effects on the body. Soothing blue capsules make more effective tranquilizers than angry red ones, except among Italian men, for whom the color blue is associated with their national soccer team—Forza Azzurri! …

AsIn the spring, Potter, who is now a VP at Merck, helped rev up a massive data-gathering effort called the Placebo Response Drug Trials Survey.  Under the auspices of the NIH, Potter and his colleagues are acquiring decades of trial data—including blood and DNA samples—to determine which variables are responsible for the apparent rise in the placebo effect. Merck, Lilly, Pfizer, AstraZeneca, GlaxoSmithKline, Sanofi-Aventis, Johnson & Johnson, and other major firms are funding the study, and the process of scrubbing volunteers’ names and other personal information from the database is about to begin.  In typically secretive industry fashion, the existence of the project itself is being kept under wraps. NIH staffers are willing to talk about it only anonymously, concerned about offending the companies paying for it.

More here.  Gee, do you think drug companies will use their better understanding of placebo effects to help us all better distinguish effective from useless drugs, or do you think they will instead use it to game the FDA approval process, to make more of their drugs look better than placebos?  What do these two theories predict about how secretive they would be about such research?

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Tetlock Wisdom

Both private- and public-sector prognosticators must master the same tightrope-walking act. They know they need to sound as though they are offering bold, fresh insights into the future not readily available off the street. And they know they cannot afford to be linked to flat-out mistakes. Accordingly, they have to appear to be going out on a limb without actually going out on one. That is why … they so uniformly appear to dislike affixing “artificially precise” subjective probability estimates to possible outcomes—the only reliable method we have of systematically tracking accuracy across pundits, methods, time and contexts. It is much safer to retreat into the vague language of possibilities and plausibilities—things that might or could happen if various difficult-to-determine preconditions were satisfied. The trick is to attach so many qualifiers to your vague predictions that you will be well positioned to explain pretty much whatever happens. China will fissure into regional fiefdoms, but only if the Chinese leadership fails to manage certain trade-offs deftly, and only if global economic growth stalls for a protracted period, and only if . . .

More here.  Hat tip to Henry at Crooked Timber.

Philip Tetlock seems to suggest that prognosticators are fooling us via this strategy, as if we would not tolerate such gaming if only we understood what they were up to.  I fear that instead we don’t much mind these games.  I suspect that we mostly want to affiliate with impressive folks, and reading their provocative forecasts gives us yet another excuse to do so.  As long no one else notices their failed forecasts enough to make them seem less impressive, we don’t really care if they were proved right or wrong.

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Pick One: Sick Kids or Look Poor

Katja is on a roll:

SODIS is a cheap method of disinfecting water by putting it in the sun. Like many things, it works better in physics than society, where its effects were not significant, according to a study in PLoS medicine recently…. [In] Rural Bolivia, where the study was done … the children studied usually get diarrhoea four times a year, which causes about fifteen percent of deaths of children under five. For the poorest quintile in Bolivia the under five death rate is about one in ten of those born alive. … The leader of the study, Daniel Mausezahl, suspects a big reason for this is that lining up water bottles on your roof shows your neighbors that you aren’t rich enough to have more expensive methods of disinfecting water. …

Fascinating as signaling explanations are, this seems incredible. … Perhaps adults are skeptical about effectiveness?  There is apparently good evidence it works though, and there were intensive promotional campaigns during the study. What’s more lack of evidence doesn’t usually stop humans investing in just about anything [medical] that isn’t obviously lethal. …. And parents are known for obsessive interest in their children’s safety. What’s going on?

The study said:

We powered the study to detect a 33% reduction in diarrhoea incidence after reviewing the evidence base for point-of-use water treatment.

So the results are (barely) consistent with the bottles working for everyone who used them, which should reduce kids’s death rate by 1.5%.   Is Katja too accepting of parent propoganda?  When are parents ever willing to make themselves appear poor or low status to reduce their kid’s chance of dying by 1.5%?

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Men Can Empathize, But Don’t

On an empathic accuracy task (inferring the thoughts and feelings of a target person) … women’s advantage held only when women were given a task assessing their feelings of sympathy toward the target prior to performing the empathic accuracy task. … Payments in exchange for accuracy improved the performance of both men and women and wiped out any difference between men’s and women’s performances. Together, the results suggest that gender differences in empathic accuracy performance are the result of motivational differences and are not due to simple differences of ability between men and women.

More here.  This isn’t exactly good news for men.  Women who think men can’t empathize probably demand less empathy than women who realize men are fully capable of empathy.  Hat tip to Robert Wiblin.

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Empathy Faces Are For Show

Our subconsciouses are like the rest of us; adeptly ‘altruistic’ when it benefits them, such as when watched. For an example of how well designed we are in this regard consider the automatic empathic expression of pain we make upon seeing someone hurt. When we aren’t being watched, feeling other people’s pain goes out the window:

A 2-part experiment with 50 university students tested the hypothesis that motor mimicry is instead an interpersonal event, a nonverbal communication intended to be seen by the other….The victim of an apparently painful injury was either increasingly or decreasingly available for eye contact with the observer. Microanalysis showed that the pattern and timing of the observer’s motor mimicry were significantly affected by the visual availability of the victim.

That is Katja Grace, who now has a blog worth watching.

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What We Do When

From this fascinating animated graph on who does what when, I’ve learned:

  • Older and better educated folks spend more time eating.
  • More educated folks eat dinner later while older folks eat earlier.
  • More educated folks and old folks sleep less.
  • Men watch more tv than women before 10pm.
  • Older folks watch more tv.
  • More educated folks watch less tv.
  • Childcare peaks at about 8:30pm.
  • Old folks exercise less, but do it earlier in the day; young folks do it later.
  • Old folks don’t shop in the evening.
  • Middle aged folks don’t sleep as much as young or old folks.
  • Most grooming is done in the morning.
  • Using computers for anything but games is still pretty rare.
  • We average much less than a minute a day of sex – way way too little!

What more can you learn from it?

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