PARTISAN ARMCHAIR STATISTICIANS: STILL HACKS. The indefatigable Daniel Davies states in lucid terms what the recent Lancet study means:
First, don't concentrate on the number 600,000 (or 655,000, depending on where you read). This is a point estimate of the number of excess Iraqi deaths - it's basically equal to the change in the death rate since the invasion, multiplied by the population of Iraq, multiplied by three-and-a-quarter years. Point estimates are almost never the important results of statistical studies and I wish the statistics profession would stop printing them as headlines.
The question that this study was set up to answer was: as a result of the invasion, have things got better or worse in Iraq? And if they have got worse, have they got a little bit worse or a lot worse. Point estimates are only interesting in so far as they demonstrate or dramatise the answer to this question...
And the results were shocking. In the 18 months before the invasion, the sample reported 82 deaths, two of them from violence. In the 39 months since the invasion, the sample households had seen 547 deaths, 300 of them from violence. The death rate expressed as deaths per 1,000 per year had gone up from 5.5 to 13.3.
What's remarkable about the embarrassingly hackish reaction of the blogosphere's professional Bush-fluffers is that I don't think they've made any argument that Davies didn't already debunk two years ago. Does Glenn Reynolds, who claims a "paucity of data" because the findings were extrapolated from 547 deaths plan on abjuring, say unemployment and polling in the future? Of course not. (The fact that he's cited a "record high" in the nominal Dow index -- itself, of course, merely a fairly small sample of the stock market as a whole -- not once but twice with the implication that the Bush economy is booming is only the most recent evidence that his support-not-illumination use of statistics bears no relationship to shame.)
But, of course, this isn't about statistics -- none of these people are going to treat sampling in other contexts as illegitimate. It's about blind (or bad) faith. Perhaps my favorite of the warblogger posts is Jane Galt's. Galt starts, promisingly, by noting that "[f]acts are not to be denied simply because you find them inconvenient," and then ... pretty much goes on to deny the facts because she finds them inconvenient. (Certainly, she has no serious critique of the methodology or data sources that aren't radically incommensurate with what the Lancet study is trying to get at.) But people like Reynolds have committed themselves to a ludicrous revisionism in which the alleged humanitarian gains were elevated from a side benefit to a central cause of the invasion of Iraq. Combined with the fact that the war cost an immense amount of money that could have been used for humanitarian purposes elsewhere, if the study is right that the invasion has been a humanitarian catastrophe it makes that justification as dead as the national security justification. So it's either pretend that the study is unfounded or admit you were wrong, and if you're still on board with the war at this late date, well...