To my previous post about Gary Taubes’s NY Times article, Andrew Gelman adds that it is good to see public discussion of these issues. I agree. I also like seeing them raised in a dramatic context: Who’s right? Powerful people making serious mistakes. How will we know? Health at risk! That sort of thing.
Speaking of drama and epidemiology . . . For many years the introductory epidemiology class for graduate students in the UC Berkeley School of Public Health was taught by Leonard Syme. I learned about this class at party. I spoke to someone who had taken it and, as a result, had switched from public policy to epidemiology. Very impressive. I knew Syme slightly. I went to his office to learn more about how he had managed to influence someone so much. “Lots of students have said that,” he told me as I entered his office. Lots of students, after taking his class, had decided to become epidemiologists. The list included Michael Marmot, one of the most important epidemiologists in the world, who studies the social gradient in health — the tendency for the people at the top to be healthier than the people at the bottom, even after controlling for all sorts of things.
The class met once/week. Every week there was a new topic. For every topic Syme would assign a paper laying out the conventional wisdom — that high cholesterol causes heart disease, for example — plus three or four papers that cast doubt on that conclusion. I think he even had American Heart Association internal emails. Several students would present the material and then there would be debate — what’s to be believed? The debates were intense. If ever the students seemed to be reaching agreement, he would say something to derail it. “You know, there was a study that found . . . ”
Practically all classes make you think you know more at the end of them than you knew when they began. Practically all professors believe this is proper and good and cannot imagine anything else. With Syme’s class, the opposite happened: Your beliefs were undermined. You walked out knowing less than when you walked in. You had been sure that X causes Y; now you were unsure. At first, Syme said, many students found it hard to take. A three-hour debate with no resolution. They did not like the uncertainty that it produced. But eventually they got used to it.
The overall effect of Syme’s class was to make students think that epidemiology was important and difficult — even exciting. It was important because we really didn’t know the answers to big questions, like how to reduce heart disease; and it was difficult and exciting because the answers were not nearly as obvious as we had been told. This is why many students switched careers.
Marmot on Syme: “I have never come across anyone in the academic world who had quite the powerful influence on students that Syme did.” Nor have I. That meeting with Syme, about five years ago, was one of two conversations in my life that really taught me something about how to teach. I was the only person at Berkeley to ever ask him about his teaching, Syme said. What a pity.