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.
Talk of confidence intervals becomes frankly irrelevant at this point. If you want to pick a figure for the precise number of excess deaths, then (1.33% - 0.55%) x 26,000,000 x 3.25 = 659,000 is as good as any, multiplying out the difference between the death rates by the population of Iraq and the time since the invasion. But we're interested in the qualitative conclusion here.
That qualitative conclusion is this: things have got worse, and they have got a lot worse, not a little bit worse. Whatever detailed criticisms one might make of the methodology of the study (and I have searched assiduously for the last two years, with the assistance of a lot of partisans of the Iraq war who have tried to pick holes in the study, and not found any), the numbers are too big. If you go out and ask 12,000 people whether a family member has died and get reports of 300 deaths from violence, then that is not consistent with there being only 60,000 deaths from violence in a country of 26 million. It is not even nearly consistent.
This is the question to always keep at the front of your mind when arguments are being slung around (and it is the general question one should always be thinking of when people talk statistics). How Would One Get This Sample, If The Facts Were Not This Way? There is really only one answer - that the study was fraudulent. It really could not have happened by chance. If a Mori poll puts the Labour party on 40% support, then we know that there is some inaccuracy in the poll, but we also know that there is basically zero chance that the true level of support is 2% or 96%, and for the Lancet survey to have delivered the results it did if the true body count is 60,000 would be about as improbable as this. Anyone who wants to dispute the important conclusion of the study has to be prepared to accuse the authors of fraud, and presumably to accept the legal consequences of doing so.
-- Daniel Davies at commentisfree.guardian.co.uk, October 12, 2006, discussing Gilbert Burnham, Riyadh Lafta, Shannon Doocy, and Les Roberts, "Mortality after the 2003 Invasion of Iraq: a Cross-Sectional Cluster Sample Survey," The Lancet (published online October 11, 2006).