Thursday, April 16, 2009

Back alley bias

Eli grew up in a semi rough neighborhood where the kids were safe, but the adults had to take care of themselves (it was a long time ago). Among the things learned were that it's the back alleys, the side streets and similar where you should not go. Thus the idea that there was a main street bias in the Lancet Iraqi death studies because people were getting blown away by bombs in markets, always struck him as strange, after all, if you live anywhere, you have to go to the market, and if you live on the back alleys, you are more exposed to other problems

Eli pointed out at Deltoid a few months ago

Robert Shone, you can't make an argument that people don't go to markets, so yes, it is likely that people from all areas go to the markets to buy stuff. You can make an argument that if it gets dangerous to go out, people will send the guys in the family and not the kids and women, and they will not linger which makes their exposure smaller, e.g. decreases the so called bias.

Now there is one exception, the people who live at the back of the store IN the market, but markets themselves are off main streets, not on them (look at the Google maps).

What is missing here is the fact that abductions will not happen on main streets as a general rule, that drive bys and abductions are a lot easier on uncrowded streets, and that the actual killings take place in isolated areas. Add to that the fact that vast housing tracts in Iraq were controlled by sectarian militias that could easily grab their victims wherever and whenever they wanted and the so-called MSB vanishes.

As Eli has been saying lo these many threads (sg is getting it), to demonstrate a bias related to proximity to main streets, you have to show that there actually is one with the available data (IBC for example), not merely throw the thought out. Otherwise you are engaged in academic onanism, a pleasant occupation, damaging to your metal and social well-being.

Now, of all things, comes Spagat in the New England Journal of Medicine, using the IBC database
The greatest proportion of victims — 19,706 of 60,481, or 33% — were killed by execution after abduction or capture. Of the bodies of those who were executed, 5760, or 29%, showed marks of torture, such as bruises, drill holes, or burns. (A typical media report about this particularly appalling form of violent death reads: "The bullet-riddled bodies bore signs of torture and their hands were tied behind their backs.") Iraqi civilians also suffered heavy tolls from small-arms gunfire in open shootings and firefights (20% of deaths), apart from executions involving gunfire, and from suicide bombs (14% of deaths).
who steps on his own line, showing that abductions, highly personal backstreet blowaways and similar were the most common source of extreme prejudice. The problem with denialists is cognitive incoherence.


1 comment:

Anonymous said...

The "back alley bias" of "T & G" is what happens when "physicists" and "mathematicians" stray into one field outside their neighborhood (into climate science).

And "Spaghetti bias" is what happens when some other physicists stray far outside their own neighborhood (into epidemiology).

What people need to bear in mind is that even if one is an expert in one area (it's not at all clear what that might actually be in the case of T&G), that does not necessarily make one an expert in any other area.

Straying outside one's own neighborhood (especially into back alleys) is often fraught with danger,