Seth's Blog

• Quotation bias in reviews of the diet-heart idea. “Criticism of the diet-heart idea is often met with the argument that consensus committees have settled the issue unanimously.” Uh, where have I heard that?
• Kefir for sale in Beijing. Eating plenty of fermented food for the first time, “for whatever reason this is first trip where I didn’t have any real bout with food poisoning or tourista.”
• Cheese and tooth decay
• Tim Harford on Jane Jacobs
• Fermented grain recipes from around the world
• Triumph over HMO. “His lack of action protected his status and his organization, but put [my daughter's] safety and well-being at risk.”
• Never bet against New Yorker writer Susan Orlean

Thanks to Steve Hansen and Gary Wolf.

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.

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%.

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.

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.