150,000 Iraqis have died violently since 2003

I wonder why the Lancet's estimate is so much higher than this one:

Post-invasion death toll in Iraq put at over 150,000

By Stephen Fidler in London and Steve Negus, Iraq,Correspondent

Published: January 10 2008 02:00 | Last updated: January 10 2008 02:00

At least 150,000 Iraqis died violently in the 40 months following the US-led invasion in 2003, according to an estimate derived from the most comprehensive survey yet of mortality in post-war Iraq.

The new estimate, based on an Iraqi government survey supervised by the World Health Organisation, falls in the middle of the two most commonly cited assessments of the death toll following the invasion. It is published in an article in the New England Journal of Medicine.

The Iraq Body Count, which uses media reports and is therefore considered likely to underestimate the actual numbers of people killed, counted 47,668 deaths between March 2003 until June 2006. A study published in the Lancet, another leading medical journal, based on far fewer household interviews, estimated more than 600,000 deaths.

There is no reliable death registration system in Iraq and the past efforts to estimate the numbers killed have become the focus of deep controversy.

The new estimate suggests violent deaths increased 17-fold when compared with the years immediately preceding the invasion. Salih al-Hasanawi, Iraq's health minister, said he viewed the survey as "very sound, based on an accurate methodology".

The article estimates with 95 per cent certainty a range of violent deaths between 104,000 and 223,000, with 151,000 the central estimate. It uses a survey of 9,345 households - five times more than the Lancet survey.

However, government researchers were unable to visit 10.6 per cent of the households they had planned to, mainly in Anbar province and Baghdad, because these areas were too dangerous. The article estimated deaths in these areas using ratios of reported deaths in the Iraq Body Count statistics.

Ties Boerma, a WHO director, said the discrepancy between the new estimate and the Lancet estimate could have derived from the smaller sample in the earlier survey that may have exaggerated results from some unusually violent areas.

Les Roberts, one of the authors of the Lancet article, said the two articles had more in common than appeared at first glance.

"The NEJM article found a doubling of mortality after the invasion, we found a tripling. The big difference is that we found almost all the increase from violence; they found half the increase from violence," he said.

He said the survey may have suffered under-reporting, because some people may have not have wanted to report deaths to government employees. The Lancet report, he said, showed a sharp jump in deaths to about 900 a day in 2005-06, an increase not reflected in the WHO-supported survey but reflected elsewhere, including in graveyards.

Since mid-2006, the IBC statistics show a sharp jump in the number of deaths, followed by a significant slowing later in 2007.