If you care to explain what this means –

This is a distinction that most people miss, because it is a very subtle one, but the (98%?) confidence interval does not mean we are 98% certain that the actual number of deaths is between 426,369 and 793,663, but that if this study were repeated with the same sample size, we are 98% confident that this other study would find between 426,369 and 793,663 deaths. Like I said, a very subtle distinction, and thus one I repeated ad nauseum when I taught my students about confidence intervals last year.

The correct statement is that if this study were repeated (with or without the same sample size) then we are 98% confident that the other study’s 98% confidence interval would include the actual number of death’s

– I’m interested. If not, carry on with your sharp rocks, and I will return to my cave dwelling.

If you don’t know what Daran’s talking about, it’s because you lack the cognitive tools to understand it…

Correct. I wasn’t trying to obfuscate. I wasn’t even replying to ungeziefer, but to someone who had indicated that he did have the cognitive tools.

And to both “Raznor ” and “Daran”: I’m afraid you’re obligated to explain in more detail what in Christ’s name you’re talking about, because at this point essentially all you’re saying is that “if you repeated the study, you’d get the same results,” without stating why this is so, or why these results are therefore incorrect.

I was replying to Raznor who in turn was responding Amp’s original post. You weren’t even in this branch of the conversation, so I don’t see how either of us are “obligated” to you in any way.

Nope. Statistics is mathematical reasoning. If you don’t have the tools, you can’t engage in the reasoning; Bayes’ theorem is akin to a sharpened rock flake. (”Those swank Cro-Magnons, coming around here with their pointy rocks thinking they’re such hot stuff…they’re just obfuscating the tool-using process!”)

I have a sufficient grounding in statistics to have a glimmering of awareness about how abysmally ignorant I am . If you don’t know what Daran’s talking about, it’s because you lack the cognitive tools to understand it, not because he’s being obscure. (NOI.)

In general, it takes an application of Bayes’ theorem to compute an a posteriori probability from an a priori probability plus additional information. The problem with confidence intervals is that we can’t do this calculation because we don’t have a value for the a priori probability that the actual death rate was between 426,369 and 793,663.

In all honesty, I minored in Philosophy in college, and I actually have no idea what you’re talking about. While that probably indicates my ignorance, I think you’re using jargon to deliberately obfuscate the truth (which is not technically a “fallacy,” but should be).

There is no “a priori” question here at all. What is needed is a serious objective look at the evidence (or “a posteriori” knowledge, if you want to sound smart), by which we can determine how many people have died.

So, in short, what the hell are you talking about????

And to both “Raznor ” and “Daran”: I’m afraid you’re obligated to explain in more detail what in Christ’s name you’re talking about, because at this point essentially all you’re saying is that “if you repeated the study, you’d get the same results,” without stating why this is so, or why these results are therefore incorrect.

Oh, and the math teacher in me has to comment on this:

But that doesn’t mean that the study is unreliable, or its methods incorrect; it just means that the results have a wide confidence interval. We can be reasonably certain there have been between 426,369 and 793,663 excess Iraqi deaths since our invasion.

This is a distinction that most people miss, because it is a very subtle one, but the (98%?) confidence interval does not mean we are 98% certain that the actual number of deaths is between 426,369 and 793,663,…

Correct. The assumption that it does, is known as the prosecutor’s fallacy.

…but that if this study were repeated with the same sample size, we are 98% confident that this other study would find between 426,369 and 793,663 deaths. Like I said, a very subtle distinction, and thus one I repeated ad nauseum when I taught my students about confidence intervals last year.

Incorrect. The correct statement is that if this study were repeated (with or without the same sample size) then we are 98% confident that the other study’s 98% confidence interval would include the actual number of death’s.

This is a very subtle point. The difference between the hypothetical study and the actual one is that we have more information about the later. We know what its confidence interval actually is. In general, it takes an application of Bayes’ theorem to compute an a posteriori probability from an a priori probability plus additional information. The problem with confidence intervals is that we can’t do this calculation because we don’t have a value for the a priori probability that the actual death rate was between 426,369 and 793,663.

Oh, and the math teacher in me has to comment on this:

But that doesn’t mean that the study is unreliable, or its methods incorrect; it just means that the results have a wide confidence interval. We can be reasonably certain there have been between 426,369 and 793,663 excess Iraqi deaths since our invasion.

This is a distinction that most people miss, because it is a very subtle one, but the (98%?) confidence interval does not mean we are 98% certain that the actual number of deaths is between 426,369 and 793,663, but that if this study were repeated with the same sample size, we are 98% confident that this other study would find between 426,369 and 793,663 deaths. Like I said, a very subtle distinction, and thus one I repeated ad nauseum when I taught my students about confidence intervals last year.

So, people went door to door and asked “how many people in your family died and when” to get pre- and post-invasion stats, eh?

This would tend to bias negatively against areas such as in Kurdistan, where when poison gas was used whole villages died, and there was no one left to ask.

I’m guessing you’re not disputing the poll here but rather trying to say that the PRE-invasion number should be much higher? In which case I can only infer that you’re talking about deaths in the 80’s and/or the first Gulf War — not terribly relevant to the “pre-invasion” figures, since the invasion happened more than 10 years later. But aside from that, your logic applies equally to the POST-invasion, since if every member of a family/household was killed (whether by U.S. troops on the ground or air strikes or insurgents or whatever), there would be “no one left to ask” — thus deflating the number.

One last point: we’re talking about a country in which the most crippling sanctions ever devised had been in effect for over a decade, in which malnutrition and disease were widespread and so forth (Madeline Albright, remember, acknowledged that half a million children had died because of the sanctions.) The fact that, more than three years after “Mission Accomplished,” the death rate is higher AT ALL is a major scandal and a tragedy. Reasonable people can ask, “are things actually worse now than they were before, in an economically crippled country run by a brutal dictator?” And that is just too sad for words.

Very good comment — we tend to think of the media as over-hyping crime and violence (”if it bleeds, it leads”), and they do. But I’m sure that even in the U.S. if we counted up every reported murder it would be less than half of the country’s homicide figure.

Like most people, my initial reaction to the figure was “that sounds too high to be plausible” — and I’m still not sure you can completely reconcile the fact that they did the same study last year (granted, with a smaller sample) and reported a figure 1/6 as high as this one (???).

But just stop an think about this: ask any soldier who comes back from Iraq “Did you kill anyone?”, and they will most likely say “Yes.” How many troops have gone over there? It’s around 140,000 - 150,000 at any given time, but those are not the same troops all serving three tours of duty. I don’t know how many individual soldiers have been deployed (maybe I’ll try to look it up), but if you figure most of them killed AT LEAST 1 person (and of course some of them killed a whole bunch of people) . . . . . I realize that’s ridiculously anecdotal and un-scientific, but it’s worth thinking about.

I do think it must be hard to get accurate numbers. But it’s interesting how things can be spun for political reasons — such as, compare this report by two well-respected medical institutions and how it’s being discredited, with the numbers that were thrown out about Milosevic’s ethnic cleansing: “100,000, 200,000, 300,000 … Well, we’re not sure, but it’s definitely up there — at any rate a massive genocide. … Etc.” Turns out the figure is no more than 11,000, and probably far less — which is still a horrific attrocity, and deserving of the term “genocide,” but my point of course is that when it’s convenient to demonize a hated enemy and make him look like the next Hitler, politicians and pundits will pull figures straight from their own arses and repeat them over and over and insist that they’re true and accurate. When it’s OUR fault, well, that’s a whole different story …

To “RonF”: I think your logic is backwards:

Like they are saying, it’s hard to do dependable research in a war zone, and I’m not sure that they can account for that by simply expanding the error bars.

So in other words, so many people are being killed that it’s too dangerous to do a poll of people killed, therefore the number of people killed must be inflated. Wha?? If anything, the opposite would be true: unable to talk to people in the most violent areas, your sample would be biased on the low side. It’s a bit like, “The problem with Iraq is that the media never report all the GOOD news — mainly cause they fear for their lives and can’t really travel freely in Iraq. If they COULD do their jobs without the constant fear of being kidnapped or killed, they’d be reportin on how everything’s goin just great over there.”

To those who don’t know, StatCan is a part of the Canadian government and responsible for carrying out censuses etc.

Here’s my point, StatCan reported that in 2000 there were 542 homicides. Note, that homicides are just one sort of violent/unexpected death-the Lancet includes other types of death-presumably some are accidental or collateral in their study. So, thats 542 murders in Canada for 2000.

Another study about the media (data for which is also from StatCan and the National Media Archive-based at Simon Fraser University in BC -http://www.media-awareness.ca/english/resources/educational/handouts/crime/our_top_story_tonight.cfm) claims that in 2000 the two major news organizations in Canada (CTV and CBC) reported on homicide 230 times. This is TV coverage and I expect that a number of these stories overlap each other. However, disregarding that fact and imagining that each story was unique only 42.4 % of homicides are reported. This is from the two most respected (and possibly representative) news organizations in the country.

The Lancet study estimates approximatley 600 000 deaths from violence in Iraq attributable to the war. IBC estimates 48 783 at the most-which they derive from media reportage. In other words, the English language media reports only 8.13% of deaths in Iraq.

The way I see it, that doesn’t seem unreasonable given that in Canada, one of the safest, literate and technologically advanced (ie. open, cheap, ubiquitous communication technology) we report on less than half of all homicides. Also consider the fact that with regard to the Iraq war it is common and accpeted knowledge that censorship of the news is necessary (e.g. DOD claiming not to keep stats, coffins returning to US etc). These are policies that the US administration readily admits to and defends. With regard to the West in general (and Canada and US in particular) local violence and murders are often big news-some might say hysterically so- and yet in our safe, open societies we still don’t report on every single homicide that occurs.

Of course the situation in Iraq even without censorship of the media is pretty much completley untenable for the type of reporting we expect in our domestic news media. With reporters almost never ascertaining ‘facts’ by first hand on-the-scene reporting (most seldom leave the Green Zone), Western media in Iraq relies on second or third hand accounts, or often enough, reports from vested interests such as the American military or various parts of the Iraqi government.

In a veritable warzone is it unrealistic to expect that violent deaths are under-reported to this extent? In fact, if anything, I’m surprised at and commend the courage of journalists there to be able to report even 8% of such news. These people are in fact war correspondents and I think can be hardly expected to get up close and personal with every story. However, the media clearly fails in that it doesn’t acknowlegde its own limitations and studies like IBC partially colude in that. This level of reporting probably can’t really be improved in the short term, but it also shouldn’t (and IBC shouldn’t) purport to tell the whole story.

Having now read and reread the study, I’m beginning to think it is better and more accurate than I thought.

[edited to remove erroneous calculation based on figure 4 and resulting snark, I should never snark at someone for a miscalculation when I myself am guilty of the miscalculation].

The number of insurgency/military/death squad related deaths reported in the news for Baghdad has been frequently reaching 100+ per day for much of 2006 (do you read juancole.com?). It was lower last fall, but around the same range or higher in the summer of 2005. The Lancet study found that 4 provinces had higher rates than Baghdad, and several others had similar rates to Baghdad. 900 per day is shocking, but that includes murders resulting from lawlessness as well as US bombing and insurgent bombing and death squads.

Also, notice figure 4, and the related discussion. A matching rise in rate of violent deaths for 2005 and 2006 were reported by the DoD program, which used a completely different methodology and covered a much more restricted category of fatalities, and by IBC estimates, which are known to dramatically underestimate death rates (most deaths don’t make the papers). So the rate of change is replicated by two other sources. It is a shocking number, but it can not simply be rejected on a “That’s too big” basis.

RonF, after your participation in the discussion of the previous study, you really can’t be treated as a creditable discussant on this subject. Go read the study, and show some sign that you understood a word of it first (you never did last time).

But I’m stil fairly skeptical. If these numbers are to be believed, then there were just under 900 violent deaths per day in the year between June 2005 and June 2006 (it’s doubled each year for the last two years). That’s 450 a day from gunshot wounds, over 150 from car bombs, and over 100 each from air strikes and other explosions. I don’t have a dog in this fight, so this isn’t an ideologically motivated skepticism—but this just doesn’t square with anything I’ve heard before. Is there anyone here who isn’t surprised by this?

This would tend to bias negatively against areas such as in Kurdistan, where when poison gas was used whole villages died, and there was no one left to ask.

Have you read the study? I just finished it. Here is is:
http://www.thelancet.com/webfiles/images/journals/lancet/s0140673606694919.pdf

The underlying assumption of statistical prediction is that the sample size is randomy selected and thus bears a random amount of variation. Because it is difficult to acheive a true random sampling, however, the assumption is generally incorrect.

Er, sample size is not randomly selected. The sample, ideally, should be randomly selected. Since that isn’t always possible, there are various techniques available to adjust for any non-randomness in the sample.

In choosing a sample size, three principles govern: Bigger is better; a law of diminishing returns apples; and the margin of error is more or less independent of the size population, provided the latter is large. What that means is that a sample of 1000 will be just as accurate for the population of the world as it is for the population of the US.

Having done a fair bit of statistics, the first thing that popped into my mind when I saw the results was “that’s odd that the difference is so huge. I wonder if they screwed up the methods or sampling?”

I say this because there the underlying math used to turn the sample into a national average is actually pretty simple. If there was anything wrong with the math I’d be surprised; it’s not as if the Lancet doesn’t have statisticians who can multiply correctly. And anyone with decent access to the paper and data–the NYT, for example–would have been able to pick up any egregious errors.

You are correct that the articles do not give details. But I’m betting that (for example) the Blendon and Barry quotes (NYT article) were made on the basis of methods and representative qualities. i’m also betting that most protests from about anyone with a stats background are also made on that basis.