OK. First of all, I haven't so much been defending the Lancet figures as attempting to show that they are not necessarily "pulled out of their asses", as Tom so eloquently put it. He seems to me shrill and wild-eyed in his derision. I actually think that the Lancet figures may be high.

What other rigorous statistical studies have been done, Tom, other than the Lancet and UN ones?

This is what I base my thoughts on:

UN Study - March 2003 to April 2004 (13 months)

War-related Death

The number of deaths of civilians and military personnel in Iraq in the aftermath of the 2003 invasion is another set of figures that has raised controversy. The Living Conditions Survey data indicates 24,000 deaths, with a 95 percent confidence interval from 18,000 to 29,000 deaths. According to the survey data, children aged below 18 years comprise 12% percent of the deaths due to warfare.

UN Study

Lancet/Johns Hopkins study - March 2003 to June 2006 (39 months)

Findings

Pre-invasion mortality rates were 5·5 per 1000 people per year (95% CI 4·3–7·1), compared with 13·3 per 1000 people per year (10·9–16·1) in the 40 months post-invasion. We estimate that as of July, 2006, there have been 654,965 (392,979–942,636) excess Iraqi deaths as a consequence of the war, which corresponds to 2·5% of the population in the study area. Of post-invasion deaths, 601,027 (426,369–793,663) were due to violence, the most common cause being gunfire.

Lancet Study (p. 1)

The interviewers then asked about births, deaths, and in-migration and out-migration, and confirmed that the reported inflow and exit of residents explained the differences in composition between the start and end of the recall period. Separation of combatant from non-combatant deaths during interviews was not attempted, since such information would probably be concealed by household informants, and to ask about this could put interviewers at risk. Deaths were recorded only if the decedent had lived in the household continuously for 3 months before the event. Additional probing was done to establish the cause and circumstances of deaths to the extent feasible, taking into account family sensitivities. At the conclusion of household interviews where deaths were reported, surveyors requested to see a copy of any death certificate and its presence was recorded. Where differences between the household account and the cause mentioned on the certificate existed, further discussions were sometimes needed to establish the primary cause of death. The study received ethical approval from the Committee on Human Research of the Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA, and the School of Medicine, Al Mustansiriya University, Baghdad, Iraq.

Lancet Study (p. 2)

Death rates have increased over the period from April 2004 (the end of the UN study) and now. I could only find the rate indicated by the Lancet study, which shows that it tripled.

The UN study does not indicate what causes are included in their death figures - they use both "war-related death" and "due to warfare".

The Lancet study indicates that 31% of violent deaths in their study were due to "coalition".

OK, let's look at the figures.

Lancet:
Total excess deaths since the invasion - 654,965 (95% confidence range 392,979 - 942,636)
Of these, due to violence - 601,027 (range 426,369 - 793,663)
Of these, due to "coalition" - 186,318 (range 132,174 - 246,036)

UN:
Deaths of civilian and military personnel, 13 months after invasion:
- 24,000 (95% confidence range 18,000 - 29,000)
Extrapolated to 39 months, no rate increase - 72,000 (54,000 - 87,000)
Extrapolated to 39 months, 1.5x rate increase - 108,000 (81,000 - 130,000)
Extrapolated to 39 months, 3x rate increase - 216,000 (162,000 - 261,000)

Without knowing how the UN attributed deaths, I think it is not unreasonable to think that they are referring to deaths caused by coalition action and direct responses to these actions - ie. due to warfare. In this case, the two studies may NOT be an order of magnitude apart, or even a factor of two apart, but actually fairly close to each other.