September 11, 2003

9/11 and the mathematics of terrorism screening

On 9/11, it feels out of place to write about anything other than the obvious. I was considering writing about why the state of civil-liberties in the US still not quite like Nazi Germany. But I'm a bit worried regarding sounding like a right-wing columnist, so I was put off of that.

There's a mathematical paradox which has been troubling me. It's a general problem, but the specifics here relate to airline screening systems, based on the two ideas:

1) Almost all people screened for terrorism will be innocent

2) Terrorists cannot be ignored

That is, a true-positive on detecting "terrorist" is a very rare occurrence, from the simple fact that there are only a handful of terrorists in existence. So any practical screening system applied to the huge numbers of people who fly each day, is going to yield almost entirely false positives. There doesn't seem to be a way to have any warning system that won't have much inconvenience.

Add in that people want the system to be as cheap as possible, and the problem becomes even harder.

I don't have a solution. If I did, I'd be trying to sell it and get rich and famous.

By Seth Finkelstein | posted in politics | on September 11, 2003 11:05 PM (Infothought permalink) | Followups
Seth Finkelstein's Infothought blog (Wikipedia, Google, censorware, and an inside view of net-politics) - Syndicate site (subscribe, RSS)

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