Today I went to a talk about terrorism. After the talk, I asked a question: What’s the evidence for the recommendations you made at the end? The speaker, a professor at Harvard, began her answer by apologizing: I can only tell you case-by-case anecdotes, she said. She repeated this apology a little later. Well, of course no one has done a controlled experiment (or any experiment) on how to deal with terrorism. Of course all we have is a story here, a story there. The speaker, whose talk was good, had heard the pervasive dismissiveness I criticize here so many times that not only did she expect it, she accepted it. The academic Stockholm Syndrome.
Month: September 2007
A Bayesian Tries SLD
Bayesian data analysis, which Andrew Gelman has pioneered, is about taking one’s beliefs into account when doing data analysis. When I wrote The Shangri-La Diet, I was being a kind of Bayesian: I realized that the facts I had gathered so far did not establish the diet as any sort of panacea. Based on the facts in the book, it was hard to say how widely helpful the diet would turn out to be. I wrote the book anyway because the facts I had gathered so far were so surprising, so inconsistent with what almost everyone said about how to lose weight. From a Bayesian point of view — taking prior beliefs into account — they were impressive. If conventional views were right, no one should lose weight following SLD. But several people had. Some of them, such as Tim Beneke, had lost a lot of weight. To complain that there was no clinical trial, no certainty, was to miss the point that the book includes data that should have been impossible.
Whoever blogs at 4d2.org says something similar:
My first reaction to [SLD] was, of course, that it was one of the stupidest things I’d ever seen. Then I started reading the forums on the creator’s (Seth Roberts) site, and then I did some Googling. And would you believe that, in the absence of anything that I would call scientific evidence, this thing seems to work for most people that try it. . . . Five days ago I honestly believed the Shangri-La Diet to be hooey — interesting hooey, maybe, but still hooey. . . I decided I’d try it for myself and report on the results. I want to make it really clear that I approached this diet with a very healthy dose of skepticism. You should also understand that I’m a staunch advocate of the “eat right and exercise, stupid” philosophy of weight loss. I have never followed a prepackaged diet strategy. Having said all that: it works. I do not know why or how it works, but it works.
How Accurate is Epidemiology? (part 2)
Because Gary Taubes is probably the country’s best health journalist, his article in today’s NY Times Magazine (”Do We Really Know What Makes Us Healthy?”) about the perils of epidemiology especially interested me. It’s the best article on the subject I’ve read. He does a good job explaining what’s called the healthy-user bias — people who take Medicine X tend to make other healthy choices as well. Does wine reduce heart attacks? Well, probably — but people who drink more wine also eat more fruits and vegetables.
The article falls short in two big ways. Taubes does a terrible job presenting the case for epidemiology. He mentions the discovery that smoking causes lung cancer but then disparages it by quoting someone calling it “turkey shoot” epidemiology. Actually, that discovery did more for public health than any clinical trial or laboratory experiment I can think of. Taubes fails to mention the discovery that too-little folate in a pregnant woman’s diet causes neural-tube and other birth defects. As the dean of a school of public health put it in a talk, that one discovery justified all the money ever spent on schools of public health (where epidemiology is taught). Taubes also fails to mention that some sorts of epidemiology are much less error-prone than the studies he talks about. For example, a county-by-county study of cancer rates in the United States showed a big change across a geological fault line. People on one side of the line were eating more selenium than people on the other side. Experiments have left no doubt that too-little selenium in your diet causes cancer.
Even worse, Taubes shows no understanding of the big picture. Above all, epidemiology is a way to generate new ideas. Clinical trials are a way to test new ideas. To complain that epidemiology has led to many ideas that turned out to be wrong — or to write a long article about it — is like complaining that you can’t take a bike on the highway. That’s not what bikes are for. If only 10% of the ideas generated by epidemiology turn out to be correct, well, 10% is more than zero. Taubes should have asked everyone he interviewed “Is there a better way to generate new ideas?” Judging from his article, he asked no one.
Now excuse me to take a selenium pill . . .
Regent Blum, Meet Provost Dumas
Richard Blum, chairman of the UC Board of Regents, rescinded a speaking invitation to Larry Summers after some UC Davis faculty complained:
After a group of UC Davis women faculty began circulating a petition, UC regents rescinded an invitation to Larry Summers, the controversial former president of Harvard University, to speak at a board dinner Wednesday night in Sacramento. The dinner comes during the regents’ meeting at UCD next week. Summers gained notoriety for saying that innate differences between men and women could be a reason for under-representation of women in science, math and engineering. . . Professor Maureen Stanton, one of the petition organizers, was delighted by news of the change this morning, saying it’s “a move in the right direction.”
Northwestern University Provost Lawrence Dumas is responsible for allowing Lynn Conway and Deirdre McCloskey to use his university’s considerable power to try to silence Michael Bailey. At Marginal Revolution, Alex Tabarrok calls the UC Regents’ action “shameful.” I agree.
Thanks to Matthew Pearson.
Abstracts from The New Yorker
The New Yorker now has online abstracts, just like scientific journals. From the abstract of an article by Patricia Marx:
The writer spies from her living-room window a multitude of colorful puffy parkas from Pucci (24 East 64th Street). The writer then calls Dr. Andrej Romanovsky to ask how the body detects cold. New York is the city of coats. Real coats, not car coats, for in this town, we walk. . . . Still worried about the coming cold? There is always one thing left to do: Miami (U.S. Airways; flights as low as $59 one-way).
Surely this is better than the article itself. Just as brandy is better than the wine it is distilled from.
Why Are Medical Costs So High?
At Cato Unbound, David Cutler, a Harvard public policy professor whose research I used in The Shangri-La Diet, writes:
The most important reason why medical costs increase over time is because we develop new ways of treating patients and provide that care to ever more people.
At least in his essay, Cutler fails to consider an alternative explanation: Medical costs have increased a lot because we have become a lot more sick — more in need of help. Over the last 50 years, obesity has greatly increased. Diabetes has greatly increased. Depression has greatly increased. Depression, including subclinical depression, is now common and has so many bad effects or correlates — less activity, less socializing, less sunlight, poor sleep, less compliance with everything — that its impact on health must be great.
Modern Veblen: Determinants of Conspicuous Consumption
At Marginal Revolution, Alex Tabarrok has an interesting post about black/white differences in what Thorstein Veblen called conspicuous consumption. It begins:
Several years ago Bill Cosby chided poor blacks for spending their limited incomes on high-priced shoes and other items of conspicuous consumption instead of investing in education.
The comments are fascinating, including this:
Merely being white is a way of signaling wealth. If you don’t believe it, visit Peru.
Why I Blog
Could this have something to do with it?
The sign says: Will listen to your story for free. Outside a Tokyo train station.
From Pearl is Culturally Confused.
More about blogging and listening.
How to Raise HDL
This piece of a discussion at the Google Group sci.med.cardiology fascinated me:
[My] HDL was always around 32, until I dropped the low fat nonsense about 7 years ago. Adding healthy fats and dropping carbs brings my HDL to about 70 while boosting my LDL almost none. And after the HDL shot up, the low-carbing continued to produce weight loss without difficulty. I’ve never felt better in my life and I am 63 now.
I would like to raise my HDL. The advice I’ve read (do a long list of things) hasn’t helped. For example, one bit of advice was to lose weight. I did lose weight and my HDL briefly got much better. I kept the weight off but my HDL did not stay high. Whereas whatever this guy did had lasting effects. I tried to find out more about what he did but, alas, he didn’t answer my email.
The View From MIT
I have blogged many times about the problems with UC Berkeley’s undergraduate education (here, here, and here, for example). For all the conventional talk about “the value of diversity”, I never see recognition of diversity of interests and diversity of skills. Everyone in a class is taught the same material (and expected to be interested in the same stuff as the professor); and everyone is graded the same way (and expected to imitate the professor). Of course, UC Berkeley is hardly unique. Practically all higher education works this way, more or less. Berkeley is just the example I know. It is a particularly egregious example given the diversity of vocational interests among its students (much more diverse than Caltech, say), its status as a public institution (with a charter to serve the public rather than its professors), and the exceptionally high research focus of its professors (making them even less interested in what students want).
At a school like Caltech or MIT, the talents of the students are closer to the talents of the professors, but I heard David Brin, the novelist, complain that after he finished Caltech with a low GPA he felt like a worthless human being. Caltech and MIT, like Berkeley, also fail to teach their students about the outside world. From an MIT professor:
Most of the sweeping generalizations one hears about MIT undergraduates are too outrageous to be taken seriously. The claim that MIT students are naive, however, has struck me as being true, at least in a statistical sense. [Could the MIT faculty have anything to do with this?] Last year, for example, one of our mathematics majors, who had accepted a lucrative offer of employment from a Wall Street firm, telephoned to complain that the politics in his office was “like a soap opera.” More than a few MIT graduates are shocked by their first contact with the professional world after graduation. There is a wide gap between the realities of business, medicine, law, or applied engineering, for example, and the universe of scientific objectivity and theoretical constructs that is MIT.
It’s Veblen again: MIT professors would rather teach “scientific objectivity and theoretical constructs” than “the [dirty] realities” of the world in which their students will spend the rest of their lives. Law schools, especially elite ones, are notoriously like this: To teach how to practice law is beneath the dignity of their professors.