Two years after the withdrawal of U.S. forces from Iraq, the war there has not ended. Levels of violence have risen to a five-year high as conflict in Syria inflames sectarian tensions. Clearly, Iraq is again on the brink, but the exact number of Iraqis killed so far this year is anyone’s guess. The Agence France-Presse puts it at 5,200, while the Iraqi government claims 3,700—a striking and telling difference.
Accounting for Iraqi war dead is a difficult task made harder by incomplete census information (the country hasn’t taken one since 1987), poor centralized record keeping, and a refugee crisis that has displaced millions.
These factors make a comprehensive count nearly impossible. And even as the death toll continues to rise, the question of how many Iraqis perished during the U.S. military’s invasion and occupation remains an open one. A new population-based study seeks an answer by estimating Iraqi casualties through the statistical method. The study, co-authored by Amy Hagopian and published in the medical journal PLOS, puts the number of deaths related to the 2003-2011 war at approximately half a million.
To be clear, this number is not an estimate of how many Iraqis were killed by U.S. forces, but instead a survey of all manner of deaths directly or indirectly caused by the war. A heart-attack brought on by increased stress, civilians killed by car bombs, Iraqi insurgents shot by American soldiers, and innocent children unintentionally slain by U.S. missiles all count together in the half million.
To derive this number, a team of researchers surveyed 2,000 Iraqi households and asked questions about the deaths of family members. Researchers extrapolated their findings to a nationwide level and compared the death rate during the war to a baseline, prewar death rate. They found the war produced a greatly increased rate of mortality by all causes, not just by violence. These nonviolent "excess deaths"—primarily from cardiovascular disease and cancer—were attributed to overloaded hospitals, the collapse of vital infrastructure, and the added stress of living in a combat zone.
That non-violent deaths are counted in the study’s total mortality rate will likely be the most controversial aspect of the report. Arguably, Iraqis who died from malnutrition, dirty water, or lack of access to basic hospital care were equally, if not directly, the war’s casualties. Moral questions of responsibility, however, cannot be adjudicated by statistics. Imagine for example an Iraqi girl who died from a preventable disease because her family would not take her to a U.S.-run clinic for fear of being labeled collaborators and targeted by Sunni insurgents, and who could not seek treatment at an Iraqi hospital because its doctors had been killed by a Shia militia. This hypothetical death would certainly be related to a war for which the U.S. bears ultimate responsibility, but would it be fair to say that the U.S. caused it?
Sometimes, assigning blame for a death is more straightforward than that. Of the half million Iraqi dead cited in the PLOS study, 132,000 were killed by injuries sustained in the fighting. This finding compares roughly to the 150,000 violent deaths (80% of them civilian) cited by the Iraq Body Count (IBC), a group that tracks killings reported in the media or by hospitals, morgues, and governments. A further source for comparison is the Iraq War Logs, the U.S. military's internal tally of casualties that registers 109,032 violent deaths in the period 2004-2009, including in that count Iraqi army and coalition troops.
Unlike the IBC and the Iraq War Logs, Hagopian’s study makes no attempt to represent the number of foreign fighters killed or to distinguish the violent deaths of Iraqi combatants from those of Iraqi civilians. However, the study’s respondents specifically attributed 35% of killings to coalition forces, 32% to militias, 11% to criminals, and 21% to unknown actors. Accordingly, the U.S. military was found to be directly responsible for killing around 46,000 Iraqi civilians and combatants over the course of the invasion and occupation.
Moral questions of responsibility, however, cannot be adjudicated by statistics.
Results indicate the car bomb, favored by al-Qaeda in Iraq, was a particularly effective psychological weapon, drawing media attention disproportionate to its lethality. The PLOS study found car bombs accounted for just 12% of Iraqi casualties. Other explosions (9%) and airstrikes (7%) also made up a relatively small percentage of the total number of violent deaths, with the majority of Iraqis (63%) reportedly dying by gunshot.
Further analysis shows 2004 and 2006-7 were the three bloodiest years of the war, followed by 2003 and 2005. Violence dropped off sharply in 2008, before starting to rise again in 2011 as US forces withdrew, just before the research concluded.
Five other population-based studies of Iraqi casualties have been conducted since the war began. Hagopian’s is the first released since 2006 and uses a new methodology based in part on the perceived failings of similar studies in the past. For example, a 2006 report that put the death toll at 654,000 in 3 years was criticized for using a flawed sampling method that inflated results. Compared to that study and the four others based in statistical analysis of the Iraqi population, Hagopian’s team used a conservative method to arrive at one of the lowest death rates.
Those seeking an exact body count will be disappointed. There is great uncertainty and potential for sampling bias built into any project like this. Hagopian acknowledges as much, asserting with 95% mathematical confidence that the actual number of war-related deaths—violent or not—was somewhere between 48,000 and 751,000, an enormous statistical range. By comparison, a proportionate range in a country the size of the United States is 475,000 to 7,473,000.
It is difficult if not impossible for us to imagine 1.3 million of our fellow citizens dying violently in the span of a few years, and millions more perishing from preventable diseases and lack of basic services, yet it appears something similar happened in Iraq. It is still happening. It’s a fair question how much responsibility each American bears for that, but it’s a question to be addressed outside the realm of science. Studies seeking to count war dead inevitably raise questions of moral culpability, but their real utility lies elsewhere. They illustrate the holistic impact of war—its true costs to an entire society—that extend far beyond the carnage wrought on the battlefield.