Category: Science
More on placebos
Alex, in his blog post from earlier today, makes a good point about placebos. Sometimes the patient is getting better anyway, and we should not attribute this effect to a placebo.
Note, however, that the best-known “anti-placebo” study is not as strong as is commonly believed. It relies heavily on a meta-analysis of other studies. Placebos appear to be effective in relieving the sufferer of pain, if nothing else. And placebos appear more effective when the ailment is continuous rather than discrete. Furthermore it is unclear how many people in the so-called no-treatment groups in fact received no treatment at all.
Here is a defense of the placebo effect. Placebos also have measurable effects in the brain, comparable to those of drugs, though weaker or less persistent.
Robert Ehrlich’s Eight Preposterous Propositions offers a very good survey of the placebo debates. His conclusion:
In summary, the [critical] study may have shown that the placebo is not as powerful as some observers would believe, but it certainly is far from powerless.
By the way, did you know that people can become addicted to placebos, or suffer from harmful “side effects”? I’ll try to write more on “nocebos,” or negative placebos, soon, at least provided that my mental attitude holds up.
Defining the Placebo Effect Carefully
I agree with Tyler that there is some serious evidence for placebo effects, especially although not exclusively for subjective components of disease. But the evidence is usually overstated because it is confused with the natural tendency of sick people to get better. A typical medical study, for example, will compare the results of a new drug against a placebo. The improvement in health of those on the placebo is then labeled “the placebo effect” – but this is wrong. To correctly identify the effect of the placebo one needs three randomly selected groups – a treated group, a placebo group and a non-treated group. The effect of the placebo per se is then measured by the health differences between the placebo and non-treated group. Although spontaneous healing effects are large, placebo effects when measured correctly tend to be small although not non-existent.
The power of suggestion
Placebos have been shown to be quite effective in treating skin warts, which are clearly not a subjective ailment and are caused by viruses. According to an Australian physician, F.E. Anderson, warts probably have the highest number of folk remedies of any disease, which is not surprising if they respond well to placebos.
From the excellent Eight Preposterous Propositions, by Robert Ehrlich.
Francis Bacon recommended treating warts with pig fat. Sometimes warts respond well to hypnotic suggestion, an effect which is not well understood. And this is from an author strongly opposed to pseudo-science.
Is it cheap corn that makes Americans fat?
Read here. Here is a short bit on the scientific developments behind cheap corn. I wouldn’t want to take any of these developments back, as they have saved millions of lives around the world. Nonetheless the biological/behavioral arguments for market failure are growing in importance (human beings did not evolve to handle fully abundant fats and sugars), relative to the traditional externalities arguments. If you don’t believe me, check back in thirty years.
Two things I learned about sleep
Old ideas that REM sleep deprivation led to insanity have been convincingly disproved…
Now I hope this second part was not funded by government money:
…although studies show that depriving someone of sleep, for example by prodding him or her awake repeatedly, can definitely cause irritability…
What else did I learn?
Body size appears to be a major determinant in the amount of sleep that a species needs. In general, the larger the animal, the less sleep it requires. Data suggest that one of the functions of sleep is to repair damage to brain cells. The higher metabolic rates of small animals lead to increased cellular injury and may, consequently, require more time for repair.
Opossums sleep eighteen hours a day, elephants three.
From the November issue of Scientific American, the article, “Why We Sleep,” is not yet on-line.
Stressed populations yield fewer males?
When a country experiences a dramatic, faltering economy, there is an equally dramatic, faltering effect on the birth rate. Specifically, there are more female births than male births, according to new research from the University of California, Berkeley. Although this phenomenon has long been observed in herd animals, this is the first time it’s been shown to happen in humans, too.
Here is the full article. Here is a press release from Berkeley. Here is Ralph Catalano’s [the researcher] home page. Here is the article itself, but the whole thing will cost you $19.00.
By the way, here is another puzzle: more boys are born in southern Europe than in northern Europe. More females are born in Mexico. Could this all correspond to stress? Here is another study, it says that stressed out parents are more likely to have girls.
My take: I can believe the result, but I haven’t much raised my priors. Note that the spike in East German female births comes in 1991, when the East German economy collapses. OK, we have found some related results elsewhere, and for other animals, that counts for a good bit in my eyes. Nonetheless I am reminded of Brad DeLong’s excellent article Are all Economic Hypotheses False?”, with Kevin Lang. If you spend enough time looking, and there is publication bias, some results will pop up, whether they are true or not. The cynical would say that behind this article, as described in the press releases, there is really only a single data point, namely 1991. N.B.: I haven’t paid the $19 to read the article itself, final judgment is reserved for those who pay and read.
Addendum: Jon Klick read the piece and sent me the following:
You’re exactly right that you’re really only focusing on one data point to identify the hypothesized effect. One wonders why he didn’t include the GDP numbers directly rather than simply including a “collapse” variable. Doing so would have allowed for more variation. If the claim is endogeneity (isn’t it always), then that’s not really solved through the collapse variable since it would be endogenous too. Also, isn’t it kind of funny how he uses a 55 year pre-period relative to an 8 year post period. If the ARIMA structure went through any significant changes around the 1991 period, you would be implicitly weighting your early data (and their ARIMA parameters) more heavily than the potentially new parameters. Thus, the 1991 change could be due to these structural parameters rather than anything GDP related; impossible to sort the effect in this design.
…[it] potentially suffers from huge omitted variable bias. That said, there are intuitive reasons to believe the thrust. Apparently, boys are more expensive in every way during the early years of life (e.g., they have more health problems which cause financial and physical drains on parents . . . this shows up in the evidence that mothers of boys die earlier and the like). Presumably then, the reproductive system has developed such that boys are spontaneously aborted when their births are likely to be most troublesome (e.g., when economic and psychological stresses are particularly acute).
Do We Need Government Science Advisors?
Chris Mooney says yes. Here is his bottom line:
In 1995, a budget-cutting Republican Congress fired its science advisers for being too politicized and too slow. In an age of bioterror, climate change, and high-tech weaponry, we need them back.
I’d like to return to this topic in the future, and the general question of whether pure science deserves government subsidy, but here is the link while it is hot.
Changes in Strange Beliefs
Here are some views that declined in popularity from 1925 to 1950. The first number is the percentage of people who believed the claim in 1925, the second number is the percentage from 1950:
1. Long, slender hands show an artistic nature: 42.0, 6.4
2. Adults can become feeble-minded from overstudy: 56.0, 10.9
3. You can closely judge a person’s IQ from his face: 50.0, 3.6
4. Women are by nature purer and better than men: 38.0, 1.8
5. The position of planets affects your character 15.0, 6.4
6. Expectant mothers can affect the character of unborn children by thought: 38.0, 2.7
From Robert Ehrlich’s Eight Preposterous Propositions: From the Genetics of Homosexuality to the Benefits of Global Warming. I’ll be blogging more about this interesting book soon.
Those six views are, of course, all preposterous. But if I had to defend one of these in a debate, I would opt for number three. Number six would come next, then number four. Number five is totally stupid, but in a way we have grown to expect. So number one seems the craziest to me.
A New Proposal for Cleaner Air
Most auto emissions come from the dirtiest ten percent of the cars on the road. Why should we ignore this fact? Daniel Klein suggests using infra-red beams to measure the quality of auto exhaust from particular cars, as they drive by the sensors. Identify the minority of gross polluters by photographing their license plates, and then get them off the road, force them to fix their cars, or tax them. Note that your annual or bi-annual auto emissions test is easy to fake or prepare for. Under Klein’s scheme the government measures the quality of auto exhaust, and lets the car owner invest in a better result however he or she wishes to do. My main worry concerns privacy issues, but perhaps privacy is headed out the window in any case. To read about related essays on economic policy and technology, from the same book, see my previous post on electricity.
Are conservatives happier than liberals?
In the 1998-2002 GSS [General Social Survey], extreme conservatives are much more likely to report being “very happy” than extreme liberals–47.1% to 31.6%. Earlier years show a similar pattern.
This conservative happiness carries over into most other aspects of life as well. Conservatives usually report being happier in their jobs than liberals. In the 2002 GSS, for example 65.2% of extreme conservatives report being “very satisfied” with their jobs in general, while only 50% of extreme liberals report being very satisfied. When the question is broadened to satisfaction with job or housework, a similar pattern obtains. In the 1998-2002 GSS, 61.0% of extreme conservatives reported being very satisfied, compared to 53.6% of extreme liberals.
As to finances, in the 1998-2002 GSS 34% of extreme conservatives report being satisfied with their finances compared to 26.4% of extreme liberals. More extreme liberals (34.5%) than extreme conservatives (25.8%) report being “not at all satisfied” with their finances.
Conservatives usually tend to report less marital unhappiness than liberals.
I am not endorsing this link, though I do find it intriguing. But might conservatives feel a greater need to claim that all is well? For the full story, pursue this link.
Doomsday scenarios collide!
Oil and gas will run out too fast for doomsday global warming scenarios to materialise, according to a controversial analysis presented this week at the University of Uppsala in Sweden. The authors warn that all the fuel will be burnt before there is enough carbon dioxide in the atmosphere to realise predictions of melting ice caps and searing temperatures.
The full story is from The New Scientist.
The economic importance of glass
Without glass:
…there can be no light switch, for there is no glass for the light bulb…There are no contact lenses or spectacles to help us.
There is no clear mirror in the bathroom to shave by, no bottles of ointment or glass for our toothbrush. There is no television in the living room, for with no screen it cannot exist. When we look out of the windows we see no cars, buses, trains or aeroplanes, for without windscreens none of them can operate (and they almost certainly have not been developed anyway). The shops in town have no window displays…
…There would almost certainly be no electricity, since its first generation depended on gas or steam turbines, which required glass for their development…Our fields would produce less than one twentieth of their current yield without the fertilisers discovered by chemists using glass tools…Telescopes, microscopes and spectacles let us see the distant and the near in ways which the human eye unaided cannot do.
From The Glass Bathyscaphe, by Alan Macfarlane and Gerry Martin (these links on the authors are more interesting than usual), a distinguished historian and an industrial expert on glass, note that Martin is also Macfarlane’s patron.
The authors examine twenty critical experiments that changed our world, chosen at random, fifteen of them could not have been performed without glass. For largely accidental reasons, glass manufacture was rising in the West while it was declining in China, Japan, and the Islamic world. Better use of glass, and better science, led to a spiral of technological improvements that enabled the rise of modern science and the Industrial Revolution. Here is a short summary article by Macfarlane.
The authors offer an on-line essay on glass in India. Here are some film clips on the importance of glass in history. Here are press reviews of the book. The authors are properly subtle and qualify their thesis in the required ways, the book is also well-written and entertaining, recommended reading.
This link will keep you busy for a long time
“The philosophers have only interpreted the world, the point, however, is to change it.” So said Karl Marx. Economists Ian Ayres and Barry Nalebuff agree, though not in a way that Marx would have imagined. Their new book: Why Not: How to Use Everyday Ingenuity to Solve Problems Big and Small offers their ideas on how to make the world a better place.
How do you feel about brake lights that indicate how fast you are decelerating?
Or how about “animal repelling devices”?
…[there are] a disturbing number of dead animals along [the road]. I personally did everything in my power to avoid hitting anything (there is a racoon on US301 that owes me his life since I nearly lost mine!) So I spent a lot of time thinking about it. Maybe a device that would be like a license plate on the front bumber, emitting ultrasonic sounds and infrared light? Wild colors, loud sounds, & flashing lights might displace the animals from the road area until things quieted down.
The new idea I need least: Movie titles at the end of movies, so you know what you just watched on TV.
The new idea I need most: A special signal for when your car is making a U-Turn.
The authors also want to offer Palestinians stock in Israeli companies, in return for a peace settlement. Here is a pre-publication New York Times review, which refers to “Daredevil Ideas from the Anti Dilberts.”
And sorry Barry, but I have to vote “no” on “colored salt,” I don’t care how bad my eyes get.
Self-deception conference
Tomorrow I am attending a conference on self-deception, directed by Robin Hanson and me. We will have numerous luminaries, including Robert Trivers and Thomas Schelling, in attendance. By the way, blogging will continue.
Here are a few self-deception pointers for the day:
However much I examine my vanity, I can’t see in it the same disagreeable tone of the vanity of other people, all of which is just a further stage of vanity.
by the poet Carlos Drummond de Andrade.
Or, did you know that Stalin, when revising his official biography for publication, ordered that this sentence be inserted:
Stalin never let his work be affected by the least shadow of vanity, presumption or idolatry.
Thomas More once wrote:
Most men like their own writing best of all.
All of these bits are from Lies We Live By: The Art of Self-Deception, by a very underrated Brazilian economist named Eduardo Giannetti. Few economists are so well-read in the humanities, so ironic at the right moment, and so on the mark in their understanding of human psychology. If anyone out there knows Eduardo’s email address, please forward it to me, I would like to write him.
Big objects in two places at once
Why do so many economists (or is it just me?) have an avid fascination with quantum mechanics? Read this article from Nature.com about a bacterium-sized mirror in two places at once. Here is the original piece of research.