Tuesday, 17 October 2006

Lancing the Lancet

Like Dan Drezner, I’m a little late to the discussion of the latest study of postwar casualties in Iraq that was recently published in the British medical journal The Lancet, following up an earlier study published in October 2004.

Setting aside the “October surprise” approach that this journal appears to be taking to these studies, there seem to be some methodological questions about the authors’ approach that are being raised; see Andrew Gelman and David Kane, the latter of whom is skeptical of the reported nonresponse rates—which do seem abnormally high, although Iraqis may be much more interested in responding to surveys than the typical citizen in developed (or even developing) countries, perhaps due to novelty effects. As David Adesnik notes, the folks at Iraq Body Count (an anti-war outfit) believe the numbers are seriously inflated as well, although this could just be a turf war among researchers rather than a legitimate grievance.

I think from my perspective the thing that jumps to mind in this discussion is “garbage in, garbage out”—basically, your statistical inferences about a population are only as good as your ability to get a true random sample and minimize response bias; this is Stats 101. These issues are problematic in developed countries, much less in countries undergoing civil upheaval, and solving them is not easy (look at the work of Leslie Kish if you don’t believe me). Does that mean that the numbers are wrong?—no, not necessarily. But my spidey sense tingles nonetheless.