Lancet Study Fundamentally Flawed: Death Toll Too High

October 19, 2006 – 1 page –
For immediate release:

Researchers at Oxford University and Royal Holloway, University of London have found serious flaws in the survey of Iraqi deaths published last week in the Lancet.

Sean Gourley and Professor Neil Johnson of the physics department at Oxford University and Professor Michael Spagat of the economics department of Royal Holloway, University of London contend that the study’s methodology is fundamentally flawed and will result in an over-estimation of the death toll in Iraq.

->The study suffers from "main street bias" by only surveying houses that are located on cross streets next to main roads or on the main road itself. However many Iraqi households do not satisfy this strict criterion and had no chance of being surveyed.

->Main street bias inflates casualty estimates since conflict events such as car bombs, drive-by shootings artillery strikes on insurgent positions, and market place explosions gravitate toward the same neighborhood types that the researchers surveyed.

->This obvious selection bias would not matter if you were conducting a simple survey on immunisation rates for which the methodology was designed.

->In short, the closer you are to a main road, the more likely you are to die in violent activity. So if researchers only count people living close to a main road then it comes as no surprise they will over count the dead.

During email discussions between the Oxford-Royal Holloway team and the Johns Hopkins team conducted through a reporter for Science, for an article to be published October 20, it became clear that the authors of the study had not implemented a clear, well-defined and justifiable methodology. The Oxford-Royal Holloway team therefore believes that the scientific community should now re-analyze this study in depth.

The team can be reached for comment at;

Gourley: s.gourley1 @ physics.ox.ac.uk mobile:+44 (0) 7733113558
Johnson: n.johnson @ physics.ox.ac.uk
Spagat: M.Spagat @ rhul.ac.uk