To Save Iraq, We Had to Kill a Bunch of Them

Or at least 655,000 (± 140,000) of them. Before I get to the news reports, I think it's important to make something clear. These statistical techniques are routinely used in public health epidemiology and nobody complains about them. Critics of this estimate can't play the same game the creationists do. They can't just debunk the numbers. They have to propose an alternative, reliable method, otherwise this estimate has to be viewed as the best available estimate. (I can't wait to hear Bill O'Reilly talk about statistics...)

From the NY Times:

A team of American and Iraqi public health researchers has estimated that 600,000 civilians have died in violence across Iraq since the 2003 American invasion, the highest estimate ever for the toll of the war here.

The figure breaks down to about 15,000 violent deaths a month, a number that is quadruple the one for July given by Iraqi government hospitals and the morgue in Baghdad and published last month in a United Nations report in Iraq. That month was the highest for Iraqi civilian deaths since the American invasion.

But it is an estimate and not a precise count, and researchers acknowledged a margin of error that ranged from 426,369 to 793,663 deaths.

It is the second study by researchers from the Johns Hopkins Bloomberg School of Public Health. It uses samples of casualties from Iraqi households to extrapolate an overall figure of 601,027 Iraqis dead from violence between March 2003 and July 2006.

The findings of the previous study, published in The Lancet, a British medical journal, in 2004, had been criticized as high, in part because of its relatively narrow sampling of about 1,000 families, and because it carried a large margin of error.

The new study is more representative, its researchers said, and the sampling is broader: it surveyed 1,849 Iraqi families in 47 different neighborhoods across Iraq. The selection of geographical areas in 18 regions across Iraq was based on population size, not on the level of violence, they said.

The Washington Post writes:

Both this and the earlier study are the only ones to estimate mortality in Iraq using scientific methods. The technique, called "cluster sampling," is used to estimate mortality in famines and after natural disasters.

While acknowledging that the estimate is large, the researchers believe it is sound for numerous reasons. The recent survey got the same estimate for immediate post-invasion deaths as the early survey, which gives the researchers confidence in the methods. The great majority of deaths were also substantiated by death certificates....

The interviewers asked for death certificates 87 percent of the time; when they did, more than 90 percent of households produced certificates.

However, it's unclear to what extent these numbers are reliable (from the NY Times):

Statistics experts in the United States who were able to review the study said the methods used by the interviewers looked legitimate.

Robert Blendon, director of the Harvard Program on Public Opinion and Health and Social Policy, said interviewing urban dwellers chosen at random was "the best of what you can expect in a war zone."

But he said the number of deaths in the families interviewed -- 547 in the post-invasion period versus 82 in a similar period before the invasion -- was too few to extrapolate up to more than 600,000 deaths across the country.

Donald Berry, chairman of biostatistics at M. D. Anderson Cancer Center in Houston, was even more troubled by the study, which he said had "a tone of accuracy that's just inappropriate."

note: The original paper is in the Lancet. I didn't link to it because it's subscription only.

Related post: Glenn Greenwald has a good post on the subject.