There are a bunch of ways to estimate how many people have died in the Iraq war. One is to keep track of news stories and official reports of combatant and civilian deaths, and add them up.
Another is to employ the tools of epidemiology and demography. Until now, we’ve had essentially only the former to rely on. That has changed with the release of a report [pdf] from the Bloomberg School of Public Health at Johns Hopkins and the School of Medicine at Baghdad’s Al Mustansiriya University, in cooperation with the Center for International Studies at MIT.
The headline-making conclusion is that the excess death toll from violent causes is estimated to be approximately 600,000 since the start of the war. This is ten times higher than other estimates, such as those by http://www.iraqbodycount.org/.
I predict that the authors of this work, their motives, and especially their conclusions, will be the subject of much uninformed debate, and more than a little derision. It has happened before, when a demographer had the temerity to contradict the US government over the death toll in the Gulf War. Her job was saved thanks to the efforts of the ACLU and the American Statistical Association. Those inclined to criticize this latest work would do well to remember their history.
Update: I neglected to provide a link to the methodological appendix (“full report” means something different to CNN than it does to me!)
Update: The Social Science Stats Blog provides further reading on the methodology.