Semi-Daily Journal Archive

The Blogspot archive of the weblog of J. Bradford DeLong, Professor of Economics and Chair of the PEIS major at U.C. Berkeley, a Research Associate of the National Bureau of Economic Research, and former Deputy Assistant Secretary of the U.S. Treasury.

Friday, October 13, 2006

55 deaths per year (2 from violence) before the invasion. Among those households, 168 deaths per year (92 from violence) since the invasion.

The Lancet study of deaths in Iraq. 47 neighborhoods. 1849 households. Among those households, 55 deaths per year (2 from violence) before the invasion. Among those households, 168 deaths per year (92 from violence) since the invasion. Scale up those sampling results to a population of 5 million households, and you have your 600,000 direct and indirect civilian casualties of war number.

And the press coverage is... incompetent and unbelievable... Why oh why can't we have a better press corps?... For example:

Here we have William Arkin of the Washington Post trying to trash the Lancet study:

600,000 Iraqis Killed By War, Credible? - Early Warning: Johns Hopkins demographers... knew that they'd need their flak jackets.... Overall, the response has been largely predictable: Tons of press coverage, those who oppose the war or represent "human rights" interests embrace the numbers, lamenting the "human cost" of war; those who support the war effort... condemn the findings....

So is there a right answer here... can reasonable non-partisan people feel comfortable with the conclusion that Iraq has suffered some 15,000 violent deaths a month every month since the U.S. invasion, some 500 deaths a day?

I think not....

There are two numbers that need to be considered in coming to a conclusion about the Hopkins' study: The raw number of deaths, and the comparison to pre-war deaths, that is, what would have been expected were there not an invasion in 2003. In the ways of sampling sizes, standard errors, reliability, and validity, the John Hopkins team claims being 95 percent certain that their 600,000 number is right. The true number -- the margin of error -- ranges from 400,000 to 900,000 deaths overall.

"To put these numbers in context," one of the study's authors says, "deaths are occurring in Iraq now at a rate more than three times that from before the invasion of March 2003."

The Hopkins team calculated Iraq's mortality rate in the year before the invasion at 5.5 deaths per 1,000 people, comparing it with their post-invasion average of 13.3 deaths per 1,000 people per year. The difference between these two rates is the rate of "excess deaths;" the deaths occurring from violence is how they get to the 600,000 number.

The entire "context" then, hinges on the validity of the pre-war mortality rate. If you accept this number, then I'm told you accept that pre-war Iraq had a better mortality rate than any other country in the Middle East, even Israel...

So I wrote Mr. Arkin a note:

Dear Mr. Arkin:

Ummmm... I'm astonished. People tell me that you are (usually) very good. But this...

Open your CIA World Factbook and look for death rates. You will find--in addition to the 5.5 per thousand number for Iraq--numbers like these: Syria 5.0... Turkey 6.0... Egypt 5.2... West Bank 4.5... Iran 5.6... Middle Eastern countries, like all countries undergoing population explosions, have young populations and so thus (with modern public health in place) low peacetime death rates.

Who told you that the 5.5 per thousand death rate per thousand was suspicious? If they knew anything, why did they lie to you? If they did not know anything, why did you trust them?

I'd appreciate a call at 925-708-0467 to talk about this.

Sincerely yours,

J. Bradford DeLong
U.C. Berkeley

I could have gone on. Perhaps I should have noted the statistical illiteracy. The Johns Hopkins team does not claim that they are "95 percent certain that their 600,000 number is right." The Johns Hopkins team claims that--if nothing has gone wrong with their study--there is a 95% chance that the confidence interval (i.e., 400,000 to 900,000) O the true number of excess deaths. THIS IS NOT ROCKET SCIENCE. This is first-semester statistics.

In a good world, the Washington Post would not employ writers who are ignorant of first semester statistics: there are lots of other people in the world who are not ignorant of first-semester statistics who could do their jobs better.

In a good world, the Washington Post would not employ writers who don't fact-check their columns.

In a good world, the Washington Post would employ writers who know that they are outside their range of competence, and take appropriate steps to inform themselves.

But let me turn the microphone over to Daniel Davies, who takes potential critics back to school:

Comment is free: The numbers do add up: The question that this study was set up to answer was: as a result of the invasion, have things got better or worse in Iraq? And if they have got worse, have they got a little bit worse or a lot worse.... The results speak for themselves. There was a sample of 12,801 individuals in 1,849 households, in 47 geographical locations. That is a big sample, not a small one. The opinion polls from Mori and such which measure political support use a sample size of about 2,000 individuals.... The Iraq Body Count website and the Iraqi government statistics are not better measures than the survey results, because one of the things we know about war zones is that casualties are under-reported....

And the results were shocking. In the 18 months before the invasion, the sample reported 82 deaths, two of them from violence. In the 39 months since the invasion, the sample households had seen 547 deaths, 300 of them from violence. The death rate expressed as deaths per 1,000 per year had gone up from 5.5 to 13.3....

[T]hings have got worse, and they have got a lot worse, not a little bit worse. Whatever detailed criticisms one might make of the methodology of the study (and I have searched assiduously for the last two years, with the assistance of a lot of partisans of the Iraq war who have tried to pick holes in the study, and not found any), the numbers are too big. If you go out and ask 12,000 people whether a family member has died and get reports of 300 deaths from violence, then that is not consistent with there being only 60,000 deaths from violence in a country of 26 million. It is not even nearly consistent.

This is the question to always keep at the front of your mind when arguments are being slung around (and it is the general question one should always be thinking of when people talk statistics). How Would One Get This Sample, If The Facts Were Not This Way? There is really only one answer - that the study was fraudulent.[1] It really could not have happened by chance.... Anyone who wants to dispute the important conclusion of the study has to be prepared to accuse the authors of fraud, and presumably to accept the legal consequences of doing so.

So what? This is always the other line from the people who want to ignore this study. Even if we accept that the invasion has been a disaster (in the strictest sense, the doubling of the civilian death-rate is usually taken to constitute a humanitarian crisis) for the Iraqi people, what should we do differently? The majority of the deaths by violence are a result of action by the insurgents, so we can't just pull the troops home. Isn't this kind of study just "picking over the rubble", to quote the Euston Manifesto and a distraction from the real debate about humanitarian intervention?

Well, there is something that we can do. We can ensure that the people responsible for this outrage suffer the consequences of their actions. A particularly disgusting theme of some right-wing American critics of the study as been to impugn it by talking about it being "conveniently" released before the November congressional elections. As if a war that doubled the death rate in Iraq was not the sort of thing that ought to be a political issue. Nobody is doing anything about this disaster, and nobody will do until people start suffering some kind of consequences for their actions (for example, no British politician, soldier or spy has lost his job over the handling of the Iraq war and no senior member of the Bush administration either)....

I would surely like to see the insurgents in the ICC on war crimes charges, but the Nuremberg convention was also correct to say that aggression was "the supreme international crime differing only from other war crimes in that it contains within itself the accumulated evil of the whole". The people who started this war of aggression need to face up to the fact, and that is a political issue.

[1] In the context of the 2004 study, I was prepared to countenance another explanation: that the Iraqis were lying and systematically exaggerating the number of deaths. But in the 2006 study, death certificates were checked and found in 92% of cases.

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