Month: June 2010

Assorted Links

Seth Roberts3 Comments

Thanks to Steve Hansen and Gary Wolf.

Probiotics Help Preterm Infants

Seth Roberts1 Comment

It has just come to my attention that a systematic review published two years ago found that probiotics help preterm infants ward off necrotizing enterocolitis. Here is a summary of the review:

Necrotizing Enterocolitis (NEC) is a serious disease that affects the bowel of premature infants in the first few weeks of life. Although the cause of NEC is not entirely known, milk feeding and bacterial growth play a role. Probiotics (dietary supplements containing potentially beneficial bacteria or yeast) have been used to prevent NEC. Our review of studies found that the use of probiotics reduces the occurrence of NEC and death in premature infants born less than 1500 grams.

The reductions in the likelihood of this disease and of death (presumably from this disease) were both greater than 50%.

Show-Off Professors

Seth Roberts17 Comments

A new Jeffrey Eugenides short story quotes Derrida. Quote 1:

In that sense it is the Aufhebung of other writings, particularly of hieroglyphic script and of the Leibnizian characteristic that had been criticized previously through one and the same gesture.

Quote 2:

What writing itself, in its nonphonetic moment, betrays, is life. It menaces at once the breath, the spirit, and history as the spirit’s relationship with itself. It is their end, their finitude, their paralysis.

“A little Derrida goes a long way and a lot of Derrida goes a little way,” said a friend of mine who was a graduate student in English. These quotes show why. In Theory of the Leisure Class, Veblen argued that professors write like this (and assign such stuff to their students) to show status. I have yet to hear a convincing refutation of this explanation nor a plausible alternative. Is there a plausible alternative?

Veblen was saying that professors are like everyone else. Think of English professors as a model system. Their showing-off is especially clear. It’s pretty harmless, too, but when a biology professor (say) pursues a high-status line of research about some disease rather than a low-status but more effective one, it does — if it happens a lot — hurt the rest of us. Sleep researchers, for example, could do lots of self-experimentation but don’t, presumably because it’s low-status. And poor sleep is a real problem. Throughout medical school labs, researchers are studying the biochemical mechanism and genetic basis of this or that disorder. I’m sure this is likely to be less effective in helping people avoid that disorder than studying its environmental roots, but such lines of research allow the researchers to request expensive equipment and work in clean isolated laboratories — higher status than cheap equipment and getting your hands dirty. I don’t mean high-status research shouldn’t happen; we need diversity of research. But, like the thinking illustrated by the Derrida quotes, there’s too much of it. A little biochemical-mechanism research goes a long way and lot of biochemical-mechanism research goes a little way.

Can John Gottman Predict Divorce With Great Accuracy?

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Andrew Gelman blogged about the research of John Gottman, an emeritus professor at the University of Washington, who claimed to be able to predict whether newlyweds would divorce within 5 years with greater than 90% accuracy. These predictions were based on brief interviews near the time of marriage. Andrew agreed with another critic who said these claims were overstated. He modified Gottman’s Wikipedia page to reflect those criticisms. Andrew’s modifications were removed by someone who works for the Gottman Institute.

Were the criticisms right or wrong? The person who removed reference to them in Wikipedia referred to a FAQ page on the Gottman Institute site. Supposedly they’d been answered there. The criticism is that the “predictions” weren’t predictions: they were descriptions of how closely a model fitted after the data were collected could fit the data. If the model were complicated enough (had enough adjustable parameters), it could fit the data perfectly, but that would be no support for the model — and not “100% accurate prediction” as most people understand it.

The FAQ page says this:

Six of the seven studies have been predictive—each began with a hypothesis about factors leading to divorce. [I think the meaning is this: The first study figured out how to predict. The later six tested that method.] Based on these factors, Dr. Gottman predicted who would divorce, then followed the couples for a pre-determined length of time. Finally, he drew conclusions about the accuracy of his predictions. . . . This is true prediction.

This is changing the subject. The question is not whether Gottman’s research is any help at all, which is the question answered here; the question is whether he can predict at extremely high levels (> 90% accuracy), as claimed. Do the later six studies provide reasonable estimates of prediction accuracy? Presumably the latest ones are better than the earlier ones. The latest one (2002) was obviously not about accurate prediction estimates (its title used the term “exploratory”) so I looked at the next newest, published in 2000. Here’s what its abstract says:

A longitudinal study with 95 newlywed couples examined the power of the Oral History Interview to predict stable marital relationships and divorce. A principal components analysis of the interview with the couples (Time 1) identified a latent variable, perceived marital bond, that was significant in predicting which couples would remain married or divorce within the first 5 years of their marriage. A discriminant function analysis of the newlywed oral history data predicted, with 87.4% accuracy, those couples whose marriages remained intact or broke up at the Time 2 data collection point.

The critics were right. To say a discriminant function “predicted” something is to mislead those who don’t know what a discriminant function is. They don’t predict, they fit a model to data, after the fact. To call this “true prediction” is false.

To me, the “87.4%” suggests something seriously off. It is too precise; I would have written “about 90%”. It is as if you asked someone their age and they said they were “24.37 years old.”

Speaking of overstating your results, reporting bias in medical research. Thanks to Anne Weiss.

Cigarettes are Bad, Right?

Seth Roberts7 Comments

My mom says her friends knew that smoking was harmful long before the Surgeon General’s report in 1962; they smoked anyway. The evidence that smoking causes lung cancer began to be accumulated in the 1950s. At first it was a radical idea. The boss of one of the scientists involved, Ernst Wynder, cut his research budget for continuing to study such a far-fetched notion.

Some of the details, indeed, did not make sense, as this fascinating essay (“The Scientific Scandal of Antismoking”, thanks to Robert Reis) points out. Were I to teach a course in scientific method, I might make this essay the first assignment: “Tell me its strengths and weaknesses.” Its strength is that it brings up new data that challenge a well-known idea (smoking causes lung cancer) that most people don’t give a second thought to. The conventional view that smoking is simply bad is surely wrong. The essay’s weaknesses are a dismissive attitude (“second-rate”) and a failure to learn from facts that don’t fit the authors’s ideas. For example, the big correlation between smoking and lung cancer that Wynder was the first to notice. What causes it? A more subtle lesson is that the big randomized controlled clinical trials are not the wonderful thing that most writers, including the authors of this essay, make them out to be (“the gold standard”). MRFIT was a hugely-expensive controlled clinical trial that produced no difference between the groups. It isn’t clear why. What can we learn from this? I’d ask my students. One lesson is the value of doing the smallest possible study — if they’d figured out the problems with a small study (and designed a better study that avoided them) they would have had a better chance of learning something from their massive study.

The Oneness of Fermentation

Seth Roberts4 Comments

A New York article about the suicide of a Dalton student contains this interesting observation. The dead boy

left filthy socks (which smelled, a cousin said, like kimchi) on his pillow

From which I conclude not only that kimchi is a good source of bacteria (“fermented foods” is a vague category — fermented for how long? — that might contain poor sources of bacteria) but also that our olfactory systems are good at detecting bacteria or more precisely bacterial byproducts. (Kimchi and used socks involve vastly different bacteria but are lumped together.) We don’t use smell to avoid predators or find food. We use vision and hearing for that. Maybe we use smell mainly to decide what to eat — to decide what contains calories (by learning smell-calorie associations, the basis of the Shangri-La Diet) and, as this observation suggests, what contains bacteria.

Mark Frauenfelder says that fermenting foods (yogurt, sauerkraut, kombucha) makes him happy.

“A Great Change is Coming” (part 1 of 2)

Seth Roberts3 Comments

In an earlier post, I wrote “A great change is coming” — meaning a great improvement in health. It will be due to better ideas. Let’s call the new ideas evolutionary thinking. They will replace gatekeeper thinking. With gatekeeper thinking, which began with shamans, you need to extract payment from sick people. Remedies and associated ideas that don’t allow this are ignored. Gatekeeper thinking pervades not only mainstream medicine but also clinical psychology, alternative medicine, and a zillion advertisements. Everyone in those fields, like the rest of us, needs to make a living. The possibility that they are doing so at the expense of the rest of us — by suppressing innovation — is impolite to bring up. Perhaps the person you are speaking to has a brother who’s a doctor. And for an enormously long time there was no alternative. A sick person doesn’t have time to do research, even if that were possible. They are forced to rely on gatekeepers, who are interested only in certain types of remedies.

Now there is an alternative — now just a glimmer, but surely growing. It has several dimensions. One is the sort of research involved. At one extreme of that dimension is original research — for example, my discovery that breakfast caused my early awakening. Gatekeeper thinking had no interest in such ideas. You could not charge for something that simple. I wrote about my discovery, with plenty of data. Anyone with web access can read it. At the other extreme of that dimension is “library research” — usually web search. An example is Dennis Mangan searching for possible cures for his mom’s Restless Leg Syndrome (RLS) and discovering persuasive stories about niacin. Again, there was no mainstream research about niacin for RLS. Anyone with web access can read what Dennis found. So for these two disorders — early awakening and restless leg syndrome — there is now a practical alternative to consulting (and paying) an expert. This isn’t repackaged folk wisdom or home remedies or someone opining. There is clear-cut data and theory involved. In the case of breakfast and sleep, it makes evolutionary sense that food would cause anticipatory activity. Likewise, the case for megadose vitamins makes biochemical sense, as Bruce Ames and his colleagues explained. You can judge for yourself.

Another dimension of this emerging space is the simplicity of the treatment. In my breakfast example, I established cause and effect with just one change: stopping breakfast. Dennis’s example also involved a simple change: megadose niacin. In contrast, Aaron Blaisdell found his sun sensitivity went away after he made many dietary changes. If you have sun sensitivity you will find it harder to duplicate what Aaron did than what Dennis or I did, but you can still come close and in any case it is a big improvement over the previous best treatment, which was to avoid the sun.

In all three cases — early awakening, RLS, and sun sensitivity — there was no gatekeeper approval. (My article with my breakfast discovery was peer-reviewed but appeared in a psychology journal rather than a medical one). In all three cases, the solution was excellent — cheap, fast, highly effective, no side effects — compared to prescription drugs (e.g., for depression). The sort of solutions that gatekeeper thinking doesn’t find. In all three cases, you don’t need to go through a gatekeeper to learn about them.

In a later post I’ll describe why I think this emerging solution space will soon become far more important.

Butterfat Good?

Seth Roberts16 Comments

I eat a lot of butter because I believe it makes my brain work better. A new paper says it may help me in other ways. From the abstract:

Compared with those with the lowest intake of full-fat dairy [= “whole milk, cream, ice cream, yogurt, full-fat cheese and custard”], participants with the highest intake (median intake 339 g/day) had reduced death due to CVD (HR: 0.31; 95% confidence interval (CI): 0.12—0.79; P for trend = 0.04) after adjustment for calcium intake and other confounders.

70% reduction is huge — so large it makes the idea of direct causation (butterfat lowers CVD risk) more plausible. (However, there is a lot of uncertainty in the estimate.) The alternative is that butterfat intake is correlated with the true cause — a behavior difference, say. But that correlation would have to be very high, which isn’t terribly plausible. Measured differences between the high-fat group and the low-fat group were small.

Stephan Guyenet reviews other evidence that supports the idea that this reduction is no fluke. Other studies have found similar effects.

Thanks to Paul Sas.