I also don’t see anything in the second Lambert quote that is at all regrettable or now-looks-false-in-the-light-of-Lancet-II. What is supposed to be wrong about what he says there?

“Whether you view it as “subtractive” reasoning or not, the 40,000 from the 100,000 have nowhere else to go.”
Viewing the deaths as having to “go” somewhere is, again, to commit the kind of subtractive reasoning that I just criticized. To think that they have to “go” somewhere is to think that htey already had to “be” somewhere in the original 100,000 number. But that’s just the mistake of subtractive reasoning. You can either defend the form of reasoning as cogent, or you can stop doing it and find a new argument. But please don’t just state it over and over again.

“It’s worth mentioning, in my view, that while the researchers had some difficulty placing some deaths in the appropriate subsets below violent and non-violent, they experienced no such difficulty determining whether a death was violent or not.” What they didn’t have any trouble categorizing was the deaths that they recoreded. The issue about statistical significance has to do with the projection out from those recorded deaths. You could be completely certain about the ones you’ve observed, while not being sure how and to what extent they reflect the population on the whole. Again, the case of the male & female Bush supporters illustrates the relevant principle here nicely. (This also applies to this statement that you make: “But I expect a study to deliver reasonable precision on the former criterion, where all interviewees can reasonably be expected to know whether a loved one died violently or not, and where a death that isn’t violent has no other option besides non-violence.” Again, accuracy in coding the sample does not entail a corresponding accuracy in the projections up to the population.)

This exchange really crystallizes what’s been going on, even from the beginning of this whole thread:

me: “you can’t convince us your study accurately reflects mortality in Iraq after regime change, if you’re not willing to break things down” Well, then I’m afraid we’re back to the point that Quiggin and others have gotten to repeatedly on this thread: y’all just need to learn some statistics. There’s just nothing wrong with defending a claim about a population without any breakdown into subpopulations.”

you: “And we’re back to the point that me and Brownie have gotten to repeatedly in this thread; population samples that can’t be defended on a breakdown basis of the main subpopulations of violent and non-violent shouldn’t be considered reliable and accurate.”

But continuing to stamp up and down on this point, even after we’ve tried so many times to explain to you why it’s wrong, does not really constitute much of an argument on y’all’s part. Several different people have tried, in several different ways, to explain to you how statistics just doesn’t support the claim that you make in that passage.

Which is why, after a while, it’s hard for various of your interlocutors to avoid pulling out the “you need to learn some statistics” card. To which you responded, “So I’ll ask you, in keeping with this passage from Tim, is it fair for you to suggest to myself and others that ” y’all just need to learn some statistics?”” At some point, I’m afraid that it is. The problem is that you keep wanting this stuff to make sense in purely intuitive terms, without recourse to the actual substance of statistical reasoning. And we’re tried with a great many different examples to make it as intuitive as we can. But at the end of the day, statistics is something that takes us beyond the intuitive, like any other specialized form of knowledge. And it is just not a legitimate demand on a specialist that he or she can make all his claims intuitive to you.

Suppose, for example, that someone didn’t know any scientific physics, and they said, “Hey, airplanes cannot possibly stay up in the air—metal is heavier than air, so it’ll fall right away.” And you can try to make the underlying physics, illustrations of the Bernoulli principle, etc. as intuitive as you can. But then suppose further that the person just said, “Well, that’s all very well, but you’re missing my point. The plane, see. It’s made of metal. And metal is heavier than air. So it’ll fall.” After enough cycles of this, you’ll want to say to the person, “hey, I’m sorry I can’t make you see how planes work, but go and learn some physics and I think you’ll see for yourself.”

Note that this isn’t even the “hey, trust us, we know the statistics” argument (which is not always necessarily a bad argument, even if it is unavoidably condescending). The argument is “hey, you don’t even trust us—go out and learn the relevant statistics yourself, you can do it pretty quickly.”

“If the study isn’t precise enough for even rough numbers for the two top subgroups, then the study should refrain from providing any figures for same.” This is a case where it is really important to keep in mind just where this was pubished. The Lancet is going to presuppose a certain amount of statistical sophistication in its readership, as well as an understanding of the norms of scientific publication in this area. It is entirely standard for these sorts of studies in any other area to report things in just the manner that these particular studies have. If you find it misleading, then that is unfortunate, but you are not part of that journal’s target readership. As long as the authors are totally up front about what is or isn’t statistically significant, then there is absolutely nothing wrong in reporting the raw numbers. You’re trying to object to these particular studies, but in this particular argument you can only do so by attacking the scientific practices more generally.

Back to you earlier posts. Sorry for the delay in replying.

“I don`t pretend to claim that this post refers to any comments of yours or not (and I`m certainly not going to drag my heels through 226 posts looking for examples of who used “gut” reasoning!)”

No? Well why not? Suck it up, man! :>)

“I certainly agree with your suspicion that the US and Iraqi governments might be selectively releasing figures. After all, the US govt doesn`t do body counts. Also suppose that a casualty count of, say, 30 dead and 45 injured on one day gets in the news – if 5 days later 35 injured die of their burns, this doesn`t hit the news at all. The media only count the deaths that occur at the moment.”

Good point on the count of those who die later from their injuries, although one of the Iraqi goverment-released figures of deaths following each month are a combined morgue-hospital report count, if I’m not mistaken. I think some of the deaths which occur days after would be captured by the hospital count, although I’ve no way of knowing for certain.

I thing someone in the Pentagon let it slip very early in the conflict that the U.S. military was keeping a count of Iraqi deaths. Their numbers have never been made public, if in fact the Pentagon is counting.

“As for the possibility that journalists are not in remote areas but hear about all the deaths there because of Iraqi activism, this seems to me to be unlikely (please forgive me if I misunderstand your post). I admit that this is an argument from incredulity, but we all know that modern media operate by waiting for press releases, and I can`t imagine that people in war-torn regions of rural Iraq are very much able to get those press-releases to the media; and even if they could, they would be dismissed by western journalists as `not credible`.”

I think the method of reporting is a function of the perceived danger posed to reporters, particularly western ones, although I’m not sure that it matters why the media there relies on briefings. I don’t think much of the western media likes George Bush or agrees with regime change. I’d be very surprised if the media would withhold reports of large scale violence in rural backwaters of Iraq, if they were occurring. I think many major media entities have an agenda, and that agenda is to undermine support for a continuing American presence in Iraq. Minimizing violence is counterproductive to that agenda.

I think it’s also important to consider scale when assessing how much violence is being missed outside Baghdad. Supporters of Lancet 2’s extremely high violent death estimate point to the 2,500 – 3,000 a month death toll that has been the norm in Baghdad since early 2006 as corroboration. Most seem to accept that the 2,500 – 3000 is accurate, and helps press their case in relation to the overall huge Lancet 2 excess death estimate.

The final period covered by Lancet 2’s survey (June 05 – June 06) claims an average monthly toll from violence of about 22,000! Critics and supporters of the war alike seem to be in agreement that the worst of the violence is far and away in Baghdad, Anbar, and the Sunni triangle. You have to assume many thousands of dead every month in areas believed to be relatively quiet, to get anywhere near this 22,000 per month average.

“These people also argue that the insurgents know this and the US army doesn`t. But if the US army has even an inkling of this philosophy behind their “plan” (or lack thereof) in Iraq, it is in their interests to discredit reports of air-strikes. So when a precision bomb precisely kills 15 kids in woop-woop-stan, if that report gets to the media unconfirmed by US troops on the ground, or by “independent” journalists at the school, the US army will immediately declare it to be a lie.”

As I mentioned in my earlier post, some of these incidents are getting reported, and not only by the decedents’ relatives. I’ve seen Iraqi officials bring claims of non-combatant deaths (from air strikes and otherwise) forward to the media as well. I agree we don’t know what percentage are getting into the media, but that goes back to the entire debate over all casualties and the accuracy of government and U.S. military released figures.

“I think we have seen evidence of this where they blew up a wedding on the Syrian border and claimed it was an insurgent hideout, until al Jazeera produced the wedding video, or photos, or some such.”

I also recall a foreign insurgent being interviewed early on in the conflict. He talked about getting into the country via the Syrian border, and how U.S. air strikes had been successful in partially interdicting the flow of foreign jihadists into Iraq from Syria. He freely admitted that whenever such an attack resulted in dead fighters, the insurgency would propagandize the deaths as non-combatants to any media willing to listen. I may still have the article saved on my hard drive. I’ll have a look for it.

“I could say, after years of living in a country with violent police, the wife of your example considers that sort of behaviour to be normal, and considers the response to be normal, not war-related.”

Yes, but we have to consider probabilities. All scenarios aren’t equally plausible. We also don’t know how many homicide deaths the study authors might be willing to assign to the same time frame as the UNDP study. Some of the overall extrapolated homicide deaths will fall into the 6 months after the UNDP study stops, so even if the UNDP study captured no deaths from homicide, the fact that the Lancet did is somewhat diluted by this difference.

“I think that the Lancet is better for its purpose because a) it confirmed 80% of the deaths through certificates; b) it ruled out deaths of soldiers (as opposed to insurgents); c) the question it asked (did someone die) is directly related to the research question (how many people died).”

I’m not that hung up on the death certificates issue, SG. I don’t think many interviewees would fabricate a death. But not capturing the deaths of soldiers makes it less likely to claim corroboration with the UNDP war related death figure, if the UNDP did capture soldier fatalities.

“The ICLS question (how many people died in war) is maybe only broadly related to the study aim…”

You’re right about that.

“So again, I maintain that did someone in this house die a war-related death is only part of the question how has Iraqi death rate changed since the invasion. Therefore, we cannot expect comparable rates between the surveys.”

Without regurgitating my entire argument, I disagree to some extent, SG. Obviously, ” war-related ” death is only a part of the overall mortality picture, since we can safely assume ” war-related” will consist almost exclusively of violent deaths. So I agree with you there, that the death rate has other elements affecting it. Still, I think you can give the Lancet every possible concession (ie, compare it’s lowest possible violent death extrapolated figure with the highest possible UNDP war-related number, exclude all homicide and soldier deaths from the UNDP figure, etc), and there’s still a sizable gap between the bottom lines for both studies in terms of violent death.

Thanks for the advice concerning statistics studies. That’s two now, you and Kevin. I think you guys speak from experience, and I’d be wise to benefit from that.

Hope all of this makes sense, SG. If not, I blame some of it on the fact that it was a rush job. I’ve got to get myself off to work shortly.

Thanks again for the insightful comments.

Thanks for your patience. SG unintentionally jumped the queue.

“I think it is quite common for statisticians to get carried away with the validity of subgroups in a study, and to act as if the point estimates of the subgroups are just as accurate as the main conclusion, even though this is not really the case. It`s a common example of scientists taking an overly positive view of their own work.”

Thanks for that, SG. Naturally, I agree with you. I think you can understand then why I find it perplexing to be chided (albeit in a gentlemanly fashion) by Philosopher when I take on the subgroups myself.

“To have a statistically significant point estimate of 100,000 excess deaths you must have some positive numbers in the subgruops of violent and non-violent deaths – you just can`t say with any precision what they are.”

I agree again, on both counts. But there’s a difference between precision and rough numbers. If the study isn’t precise enough for even rough numbers for the two top subgroups, then the study should refrain from providing any figures for same. The study authors evidently decided Lancet 1 was capable of extapolating rough estimates for the two main subgroups. On the other count, I’m not questioning the fact that Lancet 1 was absolutely correct in measuring an increase in the relative risk.

“But the biggest fallacy critics of the methodology of the study (as opposed to its value in decision making) have made in this regard is to say it is a dodgy study because it is imprecise.”

I don’t think it’s ” dodgy ” either, SG, and I know many critics have said it is, or worse. I don’t believe for a minute there was any fraud involved in the data gathering process, and in the extremely remote chance that some of the field interviewers fabricated anything (again, I don’t see it), Roberts and the rest of his study leads would be unaware and blameless.

” And regardless of how convinced you are of the accuracy of the subgroups, does it matter whether they died from cholera or a bullet? Either way they`re dead because of our war, we just don`t know exactly how many we killed directly.”

No, it wouldn’t matter how they died, SG. “How many,” matters to me even more, but I believe a study needs to convince me they’ve gotten the “how” reasonably close, at the top of the excess death chain, above bullets and cholera, before I can be convinced of the ” how many.” This is a methodology that could easily contain 10,000 extrapolated excess deaths, derived solely from a single lightning strike into a farm field, killing 4 or 5 workers. As I’ve said many times before, going back to debates over Lancet 1, the methodology is statistically sound, my disagreement lies with the methodolgy’s ability to give us an accurate picture of both the ” how ” and the ” how many ” in a place like Iraq.

It isn’t enough for me to be told ” they’re right that death has increased, why won’t you accept the ” how many ” they provide?

I can agree with the former, without agreeing they’ve got the latter right.

And we’re back to the point that me and Brownie have gotten to repeatedly in this thread; population samples that can’t be defended on a breakdown basis of the main subpopulations of violent and non-violent shouldn’t be considered reliable and accurate

Beyond that, I agree precision can’t be expected without a huge sample size. But I expect a study to deliver reasonable precision on the former criterion, where all interviewees can reasonably be expected to know whether a loved one died violently or not, and where a death that isn’t violent has no other option besides non-violence.

Philosopher, you’ve made the argument that the 100,000 figure is statistically sound, and the 60,000 figure similarly so. Whether you view it as “subtractive” reasoning or not, the 40,000 from the 100,000 have nowhere else to go. It’s worth mentioning, in my view, that while the researchers had some difficulty placing some deaths in the appropriate subsets below violent and non-violent, they experienced no such difficulty determining whether a death was violent or not.

” And my objection about your citing a 2005 quote in the present tense isn’t not cheating at all—it’s directly relevant! The point is that he wasn’t defending those claims about the 40,000 as true, he was defending them as plausible; and it’s relevant to that point that he isn’t at all trying to bother with defending them now, when there is no dialectical need to.”

I disagree, Philosopher. First of all, you’re really splitting hairs between “plausible” and “true.”

Second, splitting hairs isn’t going to cut it anyway, as this second quote from Tim illustrates:

“Rummel then takes Iraqi health ministry figures showing 3,274 deaths in military and terrorist conflicts in six months and multiplies

(Rummel): ‘by 3 to get comparable time periods, which would mean about 9,822 civilians killed by comparison to lancet’s estimate of over 100,000; 38 percent due to the terrorists versus 4 percent for Lancet. Hmmmm.’

(Lambert):” This is, of course, comparing apples with oranges. The Lancet estimate of 100,000 is of excess deaths. As well as deaths in the conflict it includes the increase in murder, accidents and disease that followed the invasion. Furthermore, the health ministry numbers are guaranteed to be an underestimate, since not every death will be recorded by Iraqi hospitals.”

Tim Lambert – RJ Rummel vs. the Lancet study – Feb 13th 2005

I think that should settle this portion of our discussion, Philosopher. In addition, I’d like to remind you of my ” apostate ” reference to Tim in my earlier post. I don’t see why Tim would argue as he has on this issue if there was a well known statistical principle he was violating by taking such a position, especially since not all of the critics he took on were innumerates like me.

So I’ll ask you, in keeping with this passage from Tim, is it fair for you to suggest to myself and others that ” y’all just need to learn some statistics?”

“Then Tim has it wrong, although I don’t believe he has, at least not when considering the implication of the first Lancet study’s data.” No, he doesn’t—because he was only defending the plausibility of the claim, not its truth. He’s just saying that the number were sensible at the time, not that they’re the way things had to be according to the study. Again, it’s just meant as a defense against a line of “No way!” type objections, to indicate that the numbers are not implausible on their face. One can make such an argument without being committed to the for-all-time truth of the numbers themselves.

And my objection about your citing a 2005 quote in the present tense isn’t not cheating at all—it’s directly relevant! The point is that he wasn’t defending those claims about the 40,000 as true, he was defending them as plausible; and it’s relevant to that point that he isn’t at all trying to bother with defending them now, when there is no dialectical need to.

I think it is quite common for statisticians to get carried away with the validity of subgroups in a study, and to act as if the point estimates of the subgroups are just as accurate as the main conclusion, even though this is not really the case. It`s a common example of scientists taking an overly positive view of their own work.

That said, I don`t know exactly how the research team described these issues, so I won`t comment anymore on it. I would expect that in the first study, given the width of the confidence interval, the subgroups are non-significant. But bear in mind that this is purely a statistical artifact, once the overall figure is significant. To have a statistically significant point estimate of 100,000 excess deaths you must have some positive numbers in the subgruops of violent and non-violent deaths – you just can`t say with any precision what they are. The second study (2006) I think serves to improve this accuracy?

But the biggest fallacy critics of the methodology of the study (as opposed to its value in decision making) have made in this regard is to say it is a dodgy study because it is imprecise. This is not a valid criticism, especially when those in govt who criticise the study refuse to fund a better one, and the only alternative study performed asks a much vaguer question. You`re right to say it may not convince non-statisticians, but this is probably why it was published in a medical journal and not a newspaper. And regardless of how convinced you are of the accuracy of the subgroups, does it matter whether they died from cholera or a bullet? Either way they`re dead because of our war, we just don`t know exactly how many we killed directly.

Yes, the 100,000 number is significant on its own terms, Philosopher, but the composition of that figure is also significant, and the authors realize that, hence their efforts to apportion it into subsets.

Put yourself in my place, as a non-statistician. I dare say there are many more of me than there are of you. If you’re Les Roberts and associates, your goal is to change public perception and public opinion in relation to Iraq. Naturally, that means you have to appeal to the reasoning processes of non-statisticians, since we’re the overwhelming majority.

Well, you can’t convince us your study accurately reflects mortality in Iraq after regime change, if you’re not willing to break things down a bit beyond a gross, best estimate aggregate number of excess dead. This is, after all, a war-related study. If there wasn’t a war involved, Roberts and Co. probably wouldn’t have done a study. War generally means you have a significant number of dead from bullets and bombs. If a mortality study can’t reliably separate the ” bullets and bombs ” victims from those who died from peacetime causes, then non-statisticians like me tend to take a jaundiced view of the entire study.

“Note that if your subtractive reasoning made sense, then we could presumably break that 100,000 number into a very large number of statistically-unmeasurable sub-sub-subpopulations (“persons aged 47 who died of a heart attack between 3pm and 4pm on a Thursday”);……”

I think you’re getting a bit hyperbolic, Philosopher. In any event, myself and others criticized the subsets of death for their volatility and unreliability for extrapolation back in 2004. That didn’t stop defenders of the study from arguing that the data at the subset level made sense, probably was reasonably accurate, and was suitable for extrapolation, which was then debated ad nauseum.

“….there would be nothing statistically significant to be said about any of those sub-sub-subpopulations, but every excess death would have been put into one of them, and so it would follow (by your reasoning) that there is nothing significant to be found about the whole!”

I don’t follow that logic, Philosopher. If you can break numbers down into minute subsets, you can reconstitute them upward again. Nothing changes. You aren’t changing the data used to break things down further, and vice versa.

“As for Tim’s earlier defense of the 40,000 figure, I think you’re misconstruing what was going on there. His arguments were only meant to show that such a number was basically plausible—not that it was an iron-clad result of the study. (At least, that’s the case with the text you quoted).”

I’m not misconstruing, and your parenthesis clad qualification kicks in here. I have many other examples of Tim arguing that the non-violent subsets reflect an increase in non-violent mortality, post-invasion.

“And it seems like it would indeed have been an entirely plausible result—it was not a crazy possibility, after all. It just turns out not to have been the case.”

Then Tim has it wrong, although I don’t believe he has, at least not when considering the implication of the first Lancet study’s data. It’s much easier for the second study to assert an unequivocal statistical no effect for non-violent excess mortality. It extrapolated a similar number of non-violent excess deaths, for a period more than twice as long as that covered by Lancet 1.

“The use of the present tense there is perhaps misleading, since I don’t think that Tim now defends those numbers as the best estimates, in light of the greater evidence of Lancet II. (Certainly quoting text from 2005 does not show that he does so.)”

That’s cheating, Philosopher. We don’t get to hop in a time capsule to revise earlier opinions and arguments, especially when Tim didn’t know if there would be a ” Lancet 2” when he voiced these opinions and arguments. I doubt Tim was a less qualified statistician then than he is now. If your argument is as statistically sound and statistically obvious as you assert, I find it incomprehensible that Tim would behave in such an apostate fashion.

Note that if your subtractive reasoning made sense, then we could presumably break that 100,000 number into a very large number of statistically-unmeasurable sub-sub-subpopulations (“persons aged 47 who died of a heart attack between 3pm and 4pm on a Thursday”); there would be nothing statistically significant to be said about any of those sub-sub-subpopulations, but every excess death would have been put into one of them, and so it would follow (by your reasoning) that there is nothing significant to be found about the whole! But I hope that it’s clear how such reasoning is going astray. Well, what doesn’t work for 100,000 subpopulations doesn’t necessarily work for 2, either. That subtractive reasoning may seem intuitively fine, but it is not correct, because going down to subpopulations may reduce the sample size such that the resulting statistics do not yield significance, even when the claims about the whole population are significant.

Someone tried much earlier to explain this in terms of an example of surveying Bush supporters, where you get 1 man and 2 women one time and 2 men and 1 woman the other time, and I think that the explanation there was pretty much on the money.

As for Tim’s earlier defense of the 40,000 figure, I think you’re misconstruing what was going on there. His arguments were only meant to show that such a number was basically plausible—not that it was an iron-clad result of the study. (At least, that’s the case with the text you quoted.) And it seems like it would indeed have been an entirely plausible result—it was not a crazy possibility, after all. It just turns out not to have been the case. So, it was not a good critique of the Lancet I study to say, “40,000 more nonviolent deaths? Inconceivable!” (which is something that lots of people at the time were saying). There are many other values that would have been plausible as well; plausibility is, all things considered, a fairly low standard to meet, but some folks wanted to argue that Lancet I didn’t meet it, and they were incorrect in doing so.

I would also point out that this is perhaps not an entirely accurate thing for you to say at this point: “one of the most prominent and statistically knowledgable defenders of Lancet 1 not only accepts that the study recorded an increase in non-violent deaths, he makes arguments to bolster the plausibility of these increases.” The use of the present tense there is perhaps misleading, since I don’t think that Tim now defends those numbers as the best estimates, in light of the greater evidence of Lancet II. (Certainly quoting text from 2005 does not show that he does so.)

I understand your argument, and I don’t disagree that the 40,000 non-violent deaths is less statistically significant and less statistically robust than the overall point estimate for excess deaths, and the excess violent death point estimate.

However, there still remains an increase in reported deaths for 4 of the 6 non-violent subsets (chronic disorders and ” other,” stayed the same). And as you see from my post #227 to John, one of the most prominent and statistically knowledgable defenders of Lancet 1 not only accepts that the study recorded an increase in non-violent deaths, he makes arguments to bolster the plausibility of these increases.

The way I see it Philosopher, the non-violent excess death extrapolation is a bit of a conundrum for defenders of the first study. In a pure statistical sense, it may not constitute an effect. Yet at the same time, the increase has to be defended, because no non-statistician would accept the survey’s 100,000 excess death point estimate if they were told that nearly half of it was considered statistically unsignificant. That’s completely counter-intuitive to any non-statistician.

You may not agree with my wording of my paragraph that you cite to start your post, but I think it quite accurately reflects this dilemma for the study authors and their supporters.

Of course, there was a solution to this dilemma. The authors could simply have cited the increase in violent death. Had they done so, you and I wouldn’t be having this exchange. I think the reason why they chose not to do so is obvious.

“Let me see if I have this right, Philosopher. Lancet 1 ” makes no claims about non-violent deaths increasing,” but adds 40,000 excess non-violent deaths to its excess death point estimate, without which the study could not achieve its headline grabbing 100,000 figure. These 40,000 excess non-violent deaths are only statisically relevant because they can piggy-back onto the excess violent ones, even though the 40,000, by themselves, represent a 22% increase over the baseline mortality estimate for the 18 month period.”

The mistake here is to think that the 100,000 number is itself derived from a calculation of the 40,000 number for non-violent, and from the 60,000 number for violent. But that’s not what’s going on. The 100,000 number is calculated on its own, and was done from a sample large enough to get the CI that has received so much discussion. The 40,000 number for non-violent deaths is derived from a smaller sample, and was not (given the baseline number of nonviolent deaths) reflective of a statistically significant difference in the number of non-violent deaths. Remember, in the pre-war period, the vast majority of deaths in this country of twenty-something million were from non-violent causes, so a fluctuation of 40,000 against that large background number might just not be—indeed, apparently wasn’t—statistically meaningful. But the 60,000 increase in violent deaths (within its CI) was also calculated independently, and did turn out to be statistically meaningful. This is the same basic idea we keep coming back to: it can be the case that a result on a sample is sufficient for significance for a whole population, even while failing to give significance for any substantially smaller subpopulation. So when you write like this

“adds 40,000 excess non-violent deaths to its excess death point estimate, without which the study could not achieve its headline grabbing 100,000 figure”

you’re missing that key point. They didn’t calculate the violent deaths, and then the nonviolent deaths, and add the resulting numbers together. Each of the three estimates—total deaths, violent deaths, nonviolent deaths—was the result of a separate, independent calculation. Two of the numbers represent point-values within a significant CI; and one of them doesn’t.

I also never got around to responding to soru at #159: “On the second, the peak of the distribution is right next to the lower CI bound, not up in the middle as would be the case for an unadjusted normal distribution.” Well, you’ve got a funny notion of “right next to”—if you look at the different scales on the two graphs, it’s actually much further from the lower bound, than the point-estimate is from the lower bound of the first graph! But perhaps your point is just that point-estimates aren’t always to be found by taking the mean of the upper and lower bounds? If so, then, yes, that’s right for certain sorts of distributions. But I don’t see how that point bears on anything I said earlier. What I said earlier was that the point-estimate is much more likely than either of the bounds. That is still very true in both graphs that you linked to.

Thanks very much for the replies. Yes, it’s one helluva long thread, but an excellent discussion all the same.

You make some solid arguments, although I don’t agree with everything.

I’m pressed for time this afternoon, I’ll have a response for you later today.

All the best…

don`t waste your time reading a stats book. I don`t think anyone needs to know much about stats to legitimately question these or any figures, and if you end up looking obtuse because you don`t know the difference between a Borel set and a sigma-algebra, well, people don`t have to answer you.

Since most people posting here have been surprised by the response rate in Iraq (because we don`t understand Iraqi culture), it`s likely we would be surprised by the reasoning behind a definition of war-related. therefore we should expect that there will be differences in surveys. I think that the Lancet is better for its purpose because a) it confirmed 80% of the deaths through certificates; b) it ruled out deaths of soldiers (as opposed to insurgents); c) the question it asked (did someone die) is directly related to the research question (how many people died). These three points are markers of a good epidemiological study – rule out confounders (b), match the question to the aim of the study (a and c). The ICLS question (how many people died in war) is maybe only broadly related to the study aim (what are your living conditions like) since arguably a better question to ask about living conditions is has anyone in your house died. Also the question involves an inherent uncertainty, because it does not confirm through a death certificate, and does not clearly define the term. This isn`t to say the answer is incorrect, just that it is not so reliable for answering the survey`s key question (what are living conditions like in Iraq).

So again, I maintain that did someone in this house die a war-related death is only part of the question how has Iraqi death rate changed since the invasion. Therefore, we cannot expect comparable rates between the surveys.

Disclaimer: I have not read the ICLS in any detail. For that matter, I have not pored over every detail of the lancet studies – I have only examined the general method and results.