Thursday, January 22, 2009

Statistics of War

I contend that the distinction between fact and opinion in unwarranted. Facts and opinions are really just varieties of statements, which are testable to varying degrees and "true" in the sense that they are supported by evidence of varying quality. So a statement like "rain yesterday" on the TV news is considered fact because it is 1) obviously testable and 2) reliable in the sense that the weatherman has been doing this for a long time and gets it right nearly every time. He also has no motive to lie, incentives to be accurate and consequences for errors. A thoughtful analysis of facts should consider the 1) supplier 2) testability 3) quality of supporting evidence. Here is an example: It was common place in the media to decry the horrors of Israel's war in Gaza. This is most easily done with a lament about the number of civilian deaths. So lets consider a factual claim made by Ethan Bronner in the NY Times on January 10th.
A tank shell landed outside the home of a family in Jabaliya, northeast of the city, killing eight members of the same family who were sitting outside, hospital officials said, bringing the death toll to more than 820. Nearly half of the dead were reported to be civilians.
Now the "fact" (i.e. Statements) here are two: 1) the death toll (820) and the 2) civilian death toll (approx 400). Let's Anaylze them closely:
  • Are these statements readily testable?
First, Hamas fighters do not wear uniforms. They fight in highly concentrated civilian areas and they readily employ young adults to provide cover. Now of course, these considerations require verification but there are abundant videos on the web that testify to these statements. Attribution of death is further complicated by cases of"friendly fire" or secondary explosions or a myriad of other inevitable accidents caused by placement of the machinery of war in the middle of a city. So the premise that casualty figures can even be determined accurately is questionable. Now this thesis itself suggests its own testable hypothesis: reported casualty figures should be inconsistent and variable. Indeed, that is exactly the case: on January 6th the NY Times reports that:
The death toll in Gaza reached around 640 on Tuesday, according to Palestinian health officials. The United Nations has estimated that about one-fourth of those killed were civilians, though there have been no reliable and current figures in recent days.
The provide a credible estimate of the intrinsic variance. First, note that on Jan 6th it was reported that out of the 640 dead 160 were civilians. Then on Jan 10th it was reported that out of the 820 dead 410 were civilians. So the reported number of total dead in the 4 days between the two Times articles grew by 180 while the number of civilian deaths (which must of course be lower than the total number of deaths) grew by 250. From this contradiction we can prove that the uncertainty in the casualty statistics is at least 100%. It is interesting, for those who like to dwell on MSM bias that the Times' reporters do not suggest that these numbers are inaccurate, only that they my be out of date.
  • Who is the supplier of these statements?
The data comes from Hospital officials- presumably Palestinian Arabs. Now hospital officals are certainly not in a position to determine civilians from fighters if the latter are not clearly identifiable. Hospital officials by definition are not on the battlefield and therefore can only communicate what they have been told. So the true "supplier" are Hamas officials and other residents.
  • What is the extrinsic variability of the data?
The intrinsic accuracy of the casualty statistics are very poor; the problem by its very nature is hard to get right. But there are enormous questions related to extrinsic factors that have nothing to do with the estimation problem directly. We have to answer two questions:
  1. What are the incentives that the actual data suppliers have to communicate honestly?
  2. Do the suppliers have a history of error?
Before answering these questions we have to find a strategy behind Hamas' war against Israel. Why do they fight at all? The battle is not even remotely even; Israel could choose to level the strip, sending Hamas as well as the civilian population to its destruction or exile. Somehow Hamas knows this will not happen. How do they know this? Certainly this is exactly how wars have taken place historically; this is what Hamas would do to Israel if they could; it is what Arab states do to each other; it is how Russia handles the Chechnyian; it is what everybody does in Africa. Hamas knows Israel will not wipe them out because 1) it hasn't yet 2) it expects and counts on the "International Community" to prevent a Western Industrialized state with few allies from exterminating a poor, long suffering, basically defenseless, third world society. So to answer question one: Why would they lie about casualties? Because it is a powerful weapon and it is their only weapon. Finally, to answer question 2: Do the suppliers have a history of error? YES. There are numerous examples of outrageously false Palestinian casualty claims: the Jenin Massacre, Muhammad Al Durah, the Gaza Beach Massacre, Green Helmet Man, Fauxtography. Ordinarily, this kind of gross manipulation should lead to an enormous credibility problem which would undermine their goals. It doesn't. Outside of the natural set of ardent supporters of the State of Israel, Palestinian Arab claims are accepted as true until demonstrated false. The quest to find an acceptable explanation for this is the hardest problem of all.