LONDON — As many as 100,000 Iraqis may have been killed, most of them by violence, as a result of the U.S.-led invasion, American public health experts estimated in a report released Thursday.
There is no official figure for the number of Iraqis killed since the conflict began, but some nongovernmental estimates had put the number between 10,000 and 30,000. More than 1,100 U.S. service personnel have died.
The scientists who wrote the report said the data on which they based their projections had "limited precision" because the quality of the information depended on the accuracy of the household interviews used.
Designed and conducted by researchers at Johns Hopkins University, Columbia University and Mustansiriya University in Baghdad, the study was published Thursday on the website of the Lancet medical journal.
The survey indicated that airstrikes from coalition forces caused most of the violent deaths, the researchers wrote.
"The use of air power in areas with lots of civilians appears to be killing a lot of women and children," Les Roberts of the Johns Hopkins Bloomberg School of Public Health said in an interview.
Oxford University's Richard Peto, an expert on study methods who was not involved in the research, said the approach the scientists took was reasonable. However, it's possible they zoned in on spots that might not be representative of the death toll across Iraq, he said.
Lancet Editor Richard Horton wrote in an editorial accompanying the survey that including more households would have improved the precision of the report, "but at an enormous and unacceptable risk to the team of interviewers."
Investigators in September visited 33 neighborhoods spread evenly across the country, randomly selecting clusters of about 30 households to sample. Of the 988 households visited, 808 agreed to participate.
Researchers asked participants how many people lived in the home and how many births and deaths had occurred since January 2002. The death rate and Iraq's estimated population were then used to estimate the number of deaths.
More than a third of the post-invasion deaths were reported in one cluster of households in the city of Fallouja, where fighting has been intense.
The death rate more than doubled after the war.
But even when the researchers recalculated the effect without the Fallouja figures, deaths were 1.5 times the rate of that before the war.