Streetwise Professor

October 23, 2010

A Noisy Signal, But Not Completely Noise

Filed under: Uncategorized — The Professor @ 9:33 pm

NPR’s firing of Juan Williams is a travesty, of course, and one that’s so obvious and so widely remarked that I see no purpose in saying any more about the firing itself.  One thing that has struck me, though, is the analysis of Williams’s words.  In particular, the frequent statement that Williams’s fears of those in traditional “Muslim dress” were irrational because terrorists would try to blend in.

One example:

If anything, an Islamist terrorist wants to blend in, not stand out.


In this, [Williams] was simply acknowledging an anxiety that is felt by millions of Americans who fly.

This may not be entirely rational (the odds of being victimized by terrorism are very small), and Muslim garb is an unlikely marker of a terrorist in a U.S. airport anyway (a terrorist is likelier to try to fit in).

Williams’s fear was not entirely rational (though not entirely baseless, either).  But the “terrorists would try to fit in, not stand out” critique of is reasoning is unpersuasive.

It is unpersuasive because as a matter of policy, the adamant refusal of security personnel to profile as a matter of policy means that wearing such dress would have little if any effect on the likelihood of the wearer being subjected to additional scrutiny.  (Whereas my wife, who would fit no non-insane terrorist profile known to man was harassed by TSA in the St. Louis airport yesterday, although that could have been best explained as the actions of a twisted TSA agent abusing the new body scanning equipment.  Probably a good thing I wasn’t there.)

And as for Islamic terrorists trying to fit in, and avoiding Islamic dress, just as recollecting that one black swan is sufficient to disprove the hypothesis that all swans are white, it is useful to recall the events of about a year ago.  For that is when Major Nidal Hasan, the Fort Hood assassin, regularly paraded about in such garb.  Including on the day that he committed the murders:

An owner of a 7-Eleven at Fort Hood said Hasan — whom he knows as “Major Nidal” — came in for coffee and hash browns most mornings, including the morning of the shootings. Surveillance video from the store obtained by CNN shows a man who according to the store owner is Hasan at the cashier’s counter at about 6:20 a.m. Thursday, about seven hours before the mass shooting. He was carrying a beverage and dressed in traditional Arab garb.

In brief, Juan Williams’s fears were not based on careful analysis–and certainly, few fears are, and Williams forthrightly acknowledged that–but the analysis of those who critiqued those fears are hardly persuasive.  Williams wasn’t consciously being a Bayesian, but a coldly calculating Bayesian would not disregard Islamic dress in assessing the odds that an individual is a potential terrorist.  Those odds are extremely small in any individual case, including cases of individuals wearing said dress, but this is not a piece of data that should be discarded as wholly uninformative.  If Hasan’s superiors had taken note of his clothing preferences, especially in light of other information, the 14 people he murdered might be alive today.

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