Iraq death rate study defended18th October 2006
Francesco Checchi, an epidemiologist at the London School of Hygiene and Tropical Medicine, looks at the lambasting a new report on Iraq deaths has got from hostile governments.
He has worked on mortality surveys in Angola, Darfur, Thailand and Uganda, and written a publication "Interpreting and using mortality data in humanitarian emergencies" for the Humanitarian Practice Network:
Reaction to the latest estimates of conflict-related death toll in post-invasion Iraq - about 655,000 according to a study published by a joint U.S.-Iraqi team in the eminent medical journal The Lancet - re-confirms a worryingly unscientific trend in reporting and discussion of the effects of modern conflict on human health.
Commenting on mortality estimates, especially when they suggest that a war initiated on disputed grounds has resulted - and continues to result - in catastrophic loss of life, should be done with the greatest caution.
The choice of method is anything but controversial. In theory, representative household surveys are always a better approach than body counts, which, as Burnham et al. point out in their interesting discussion, have always turned out to significantly under-estimate true death tolls.
There's nothing wrong about estimation per se, so long as one provides a confidence range (which in this case we have); provided that the sample size is reasonable (it is), the only risk is to incur in some error unrelated to sample size (bias), such as, for example, systematically interviewing households that were particularly affected by violence, or getting distorted information from interviewees.
The Lancet survey does not perform "extrapolation" from a small sample, as the British government claims. It estimates a death rate, and merely applies it to the time period, and population, within which that death rate was measured - a statistically transparent procedure, given that the survey covered the entire country with the exception of two Governorates.
It is not the case that every point in the confidence interval range is equally likely. In fact, assuming that there was little bias, the true death toll is much more likely to be close to the point estimate (655,000) than to the lower (393,000) and upper (943,000) bounds of the confidence range. It isn't a dartboard.
The survey features a lot of compelling aspects - for example, reported deaths were certifiable; non-violent death rates were broadly consistent with pre-war conditions, suggesting no over-reporting by families; the profile and typology of violent deaths reflects what is expected; and, crucially, findings mirrored closely those of a previous Hopkins/Mustansiriya survey in 2004.
But in Iraq today, insecurity has made it almost inhumanly difficult to conduct proper research on the harms and benefits of war. Indeed, what both media and pundits seem to never highlight as a deeply troubling anomaly is that, were it not for the work of a few courageous researchers such as the Hopkins/Mustansiriya University team, or the painstaking work of concerned members of the citizenry such as the Iraqi Body Count project, quantifying the effects of the U.S.-led intervention on human health would largely be a matter of divination.
The Lancet study is fast disappearing off the news headlines. Dismissing and, worse, ignoring this and other alarming findings simply because "they sound wrong" is no way to move forward - if they can't be proven wrong (or partly wrong) on scientific grounds, they must certainly stand, until better evidence emerges.
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Title: Iraq death rate study defended
Author: Luisetta Mudie
Article Id: 941
Date Added: 18th Oct 2006