Interesting discussion on Tim Lambert's 41 post on the Lancet 100,000 death study. SoldierDad has an excellent point here as well, noting that Iraq's pre-war death rate seems incredibly low -- lower even than the EU death rate(!). That would seem to fail the laugh test. I'm guessing one reason besides the one he mentions is that when Saddam's goons dragged you off to be tortured to death for drawing a funny beard on a Saddam portrait, they probably weren't that fastidious about doing all the paperwork.
Here are what I thought were the more interesting and relevant comments:
TallDave 21/3/2005 05:01:39
Binomial, I would think, but both are reasonably approximated by a normal distribution in this case
There is no basis on which to make that statement. The data barely even produces a significant correlation for the confidence interval itself, so to pretend you can describe the distribution within it is laughable.
Yes, the 95% confidence interval by itself doesn’t tell us what the probabilities are. But this doesn’t mean that each value is equally likely. We can also construct other confidence intervals. We can be 67% confident that the number is between 50,000 and 150,000. In this sense the end points of the 95% CI are less likely and the middle is most likely.
No, you can't. Besides the fact a 67% probability is practically meaningless (that's a 1 in 3 chance the effect doesn't even exist), the 67% probability bounds speak only to the 67% probability interval. They tell you NOTHING about any other interval. Every number from 8,000 to 194,000 is 95% likely. They are all equally probable, and none of them is "more equal" than the others.
TallDave 21/3/2005 05:15:52
I'm sure this point has been made before, but just to make it again: The main reason reason the study is worthless is because all it can conclude with a 95% confidence interval is that something happened which created between 8,000 and 194,000 additional deaths. This is not useful. We already know the war probably killed more than 8,000 and less than 194,000. The study tells us nothing new or useful -- unless someone arbitrarily grabs a number with no confidence interval to bandy about as an "estimate."
Tim Lambert 21/3/2005 05:24:18
TallDave, it is absolutely false to say that each number in the 95% CI is equally likely.
Pat Curley, for deaths before the war see link
The study did not just count violent deaths but all deaths. Part of the increase was an increase in deaths from disease.
TallDave 21/3/2005 05:24:41
You know, if the authors wanted to be honest about that 100,000 number, they would have to say "We believe 100,000 people were killed, but our confidence level for the 100,000 +/- 0 range is approximately ZERO percent. Any single-number estimate is just a guess and nothing more."
Soldier's Dad 21/3/2005 05:25:19
The mortality rate for the EU is 10/1000.
The mortality rate for the World is 8.81/1000.
The mortality rate for Iraq according to Lancet is 7.9 /1000. The base line death rate(needed to calculate excess deaths) would mean Iraq had one of the lowest mortality rates in the world in 2002.
As "food rations" were determined by family size, and it is largely accepted that the rations were not nearly enough, it is an easy leap to question whether family's might have hidden deaths in order to maintain the additonal ration. The Lancet study does nothing to determine whether the 2002 mortality rate in Iraq, which would have made Iraq one of the healthiest places on the planet, was in fact accurate.
TallDave 21/3/2005 05:25:29
No Tim, it is absolutely false to claim you can say which numbers within that interval are more likely than the others. The range is a quanta.
I suppose technically I am in error to say that no conclusions can be drawn about the interval data (esp. since you could use sources outside the study itself); but it is certainly true that no meaningful (i.e. 95% confidence) connclusions about ranges within the interval can be made on the basis of the numbers in the study. The whole reason you do the 95% confidence interval in the first place is to make meaningful conclusions; when you start parsing the interior of the interval based on other intervals you are flailing at them with non-meaningful correlations. So that point stands, with this clarification.
As I pointed out above, the 100,000 number is statistically meaningless as it has confidence of essentially zero. The only meaningful statement that can be made from this study is that the number of dead is between 8,000 and 194,000.