New Estimate of Violent Deaths Among Iraqis Is Lower

Les Roberts, an epidemiologist now at Columbia University who helped direct the Johns Hopkins survey, also praised the new one. While both found a large increase in mortality, his found that much more of it was caused by violence.

"My gut feeling is that most of the difference between the two studies is a reluctance to report to the government a death due to violence," he said. "If your son is fighting the government and died, that may not be something you'd want to admit to the government."

The new study was conducted between August 2006 and March 2007 in all regions of the country, including the Kurdish northern area. Surveyors visited about 1,000 randomly selected geographic areas (called "clusters") and interviewed people in 9,345 households. They were asked whether anyone in the household -- defined as people living under the same roof "and eating from one pot" -- had died from June 2001 through June 2006.

Each death was assigned to one of 23 causes. "Violent death" covered shootings, stabbings, bombings and other intentional injuries, and included civilian, military and police deaths but not suicides and traffic fatalities unrelated to roadside bombs.

Danger prevented surveyors from visiting 11 percent of the chosen clusters. Deaths in those areas were estimated using the ratio of deaths in the region to deaths in other regions as found in the Iraq Body Count, a continuous count of reported and verifiable violent deaths of civilians kept by an independent, London-based group. (That count, which even its organizers agree misses many deaths, registered 47,668 deaths from the U.S.-led invasion through June 2006).

Previous research has shown that household surveys typically miss 30 to 50 percent of deaths. One reason is that some families that have suffered violent deaths leave the survey area. Demographers think that as many as 2 million Iraqis have fled the country since the war began, and the 151,000-death estimate includes an adjustment for this.

Calculating death tolls in Iraq has been notoriously difficult.

Some people are kidnapped and disappear, and others turn up months or years later in mass graves. Some are buried or otherwise disposed of without being recorded. In particularly violent areas, local governments have effectively ceased to function, and there are ineffective channels for collecting and passing information between hospitals, morgues and the central government.

One senior Health Ministry official, who spoke on the condition of anonymity, said there are detailed casualty numbers, but "we have strict instructions not to give them out." The U.N. human rights mission in Iraq has criticized the Iraqi government for withholding information on civilian casualties.

Last month, Gen. David H. Petraeus, the top U.S. commander in Iraq, provided a U.S. military chart on civilian deaths in Iraq between January 2006 and December 2007, but specific monthly tolls were not included. A rough estimate based on this chart, which synthesized Iraqi and U.S. figures, indicated that some 40,000 civilians had died in the past two years in Iraq.

Jalil Hadi al-Shimmari, who oversees the western Baghdad health department, said the 151,000 total seems roughly accurate but is probably a "modest" one. "The real number might be bigger than this," he said.

The study employed about 400 interviewers. Some were employees of the Iraq Health Ministry, and others were local health workers, such as pharmacists, midwives and nurses. Women surveyors were used to interview women in the households. Different religions and sects were represented.

"They built up the trust of the community, especially in the difficult areas," said Naeema al-Gasseer, WHO's representative in Iraq.

One Iraqi official working on the survey was killed in random violence on the way to work. A few interviewers were detained by local militia under suspicion they were spies. One surveyor was kidnapped and ransomed.

"They did risk their lives. There was a determination to make it a success," Gasseer said.

Partlow reported from Baghdad. Staff writer Josh White contributed to this report.