A great piece of science journalism

I really enjoyed this New York Times article about scientists measuring the melting of Greenland's ice sheet.  It has so many great elements:

beautiful images and video. We often think of science as complicated and abstract, but the beauty of nature is what drives a lot of us to keep at it.  Capturing our work with a beautiful image is a worthy goal for scientists who want the public to be able to relate to their work.  In this article, the images and video are especially well integrated into the text, rather than standing apart from it.

the whole story of the research.  Too often we see just the final result, but this article explains so much more: why the team thinks the research is worthwhile, how they got funding for it, how hard they work, and how persistent and creative they are at problem-solving in pursuit of their measurements.

scale: this is one of the most difficult things for scientists to convey.  This team is measuring the melting in one small part of the ice sheet, but with the hope of extrapolating to the entire ice sheet.  The article literally zooms in from a view of all Greenland to a view of the campsite, and then---very importantly---zooms us back out to see the big picture again.

we practice thinking scientifically. Even those who are quite familiar with the basics of global warming and sea level rise will learn an important nuance: models of ice melt are far cruder than the reality.  The greater the extent to which these rivers flow under the ice sheet, the faster we may lose the ice sheet and get truly substantial sea level rise.  These measurements will help us improve the model and therefore the forecast.  This article also shows how good scientists withhold judgment until the facts are in: although massive ice loss is an alarming prospect, the team "might even learn...that the water is refreezing within the ice sheet and that sea levels are actually rising more slowly than models project."

Good job, NYT!  This is a model for science journalism.

Fallacy of composition

Paul Krugman's column yesterday focused on an application of the fallacy of composition: the false belief that what is true of the parts must be true of the whole. This is one of my favorite fallacies to teach because I never learned about it as a student and it can be surprisingly counterintuitive.

Imagine that one year growing corn turns out to be more profitable than growing soybeans. The logical thing for each farmer to do is plant more corn the next spring; in fact to maximize your profit you should plant all your fields in corn, right? But if all farmers do this, corn prices will plummet and soybeans will become very valuable. Planting a lot more corn is a logical thing to do for one farmer, but not for farmers as a whole.

Krugman's column does not use the term fallacy of composition, but it is essentially the same idea for debt: each family has to balance its budget, so the government has to also, right? Wrong. When I was younger I swallowed this argument hook, line, and sinker when I heard it from politicians. But the analogy is false. When society as a whole goes into debt, it goes into debt to itself, or some subset of itself. The dynamic is completely different, because this type of borrowing can spur the economy as a whole.  This is not to say that government debt is always harmless, but those who make debt-is-harmful arguments should at least give substantive reasons rather than a false analogy. Any politician who makes this analogy now instantly loses all credibility with me.

A related effect is Simpson's paradox. A school may have improving test scores for each racial/ethic group individually, but it can still be true that the school as a whole has decreasing test scores. How? The racial/ethnic composition of the school is changing, with more disadvantaged groups living in the area. This brings the overall average down regardless of improvements within each group.

I taught this fallacy when I taught a first-year seminar in scientific reasoning, and it may seem like one of those counterintuitive puzzles that has little application in the real world. But Krugman's final sentence reminded me of the real-world importance of effective reasoning: "if the euro does fail, here’s what should be written on its tombstone: 'Died of a bad analogy.'”

Number needed to treat

The New York Times' Upshot series has an excellent article on visualizing medical statistics today. This is a great way to learn how to think about numbers that affect your life.