Researcher Discovers Effective Profiling; Says It's More Trouble Than It's Worth

By Eliza Strickland | February 3, 2009 5:07 pm

airport security“Flying while Muslim” is the new “driving while black”, according to air travellers who believe they are being targeted for extra security measures on the basis of racial and religious profiling [New Scientist]. The Transportation Security Administration is mum on whether they use racial profiling in deciding who to pull out of line at airport security, and also won’t give details as to whether it scrutinizes air travelers’ behavior (like when and how they bought their tickets, or whether they have checked luggage). But a new mathematical study suggests that any such profiling is not the most effective way to find a terrorist lurking in a crowd of ordinary people.

At first glance, the profiling approach seems logical, despite many people’s moral objections. If all previous acts of politically motivated terrorism have been committed by a particular nationality, then doesn’t it make sense to focus searches on those groups? Not necessarily, says William Press of the University of Texas at Austin. Do the maths and you discover that a simple-minded application of these actuarial methods is worthless: all you end up doing is repeatedly picking out the same innocent people [Nature News].

In the study, published in the Proceedings of the National Academy of Sciences, Press modeled situations in which members of a profiled group are, for example, 100 times more likely to be a terrorist than a typical traveller. You might think that the best approach would be to make it 100 times more likely that these people are selected for extra security checks. But in fact, random screening turns out to be just as effective. The problem is that too much time is spent repeatedly screening members of the profiled group who are not actually terrorists, Press explains [New Scientist].

Press did find a slight benefit to profiling in a weakened form. Mathematically speaking, it would be optimal to screen individuals in proportion to the square root of their presumed probability of malfeasance [Scientific American]. Using this “square-root-biased sampling,” a member of a group that is considered 100 times more likely to contain terrorists would be 10 times more likely to get extra screening. This would distribute resources more evenly, effectively casting a wider net and catching more would-be terrorists.

But Press says real-world terrorist profiles are notoriously hard to construct, and it’s extremely unlikely that any group–be it an ethnic group or people who pay cash for their tickets–could be considered 100 times more likely to contain terrorists. A more realistic probability factor might be 10, and taking the square root of that means that members of the group would be only about 3 times more likely to receive extra screening. Press says that at that point the profiling is so watered down and the benefit is so small that this should “reopen the moral and ethical questions of whether the profiling is worth the social cost at all,” he says. “Personally, I would say that it is not” [Scientific American].

Related Content:
DISCOVER: The No-Touch Pat-Down describes the “air puffer”
DISCOVER: Future Tech: facial recognition systems in airports
Discoblog: Co-Ed Naked Airport Security: X Ray Scanners Strip Search Passengers

Image: flickr / nedrichards

  • nick


  • Christopher White

    “The Transportation Security Administration is mum on whether they use racial profiling in deciding who to pull out of line at airport security…”

    This is wholly inaccurate. The TSA has been extremely clear that it does not profile and that in fact it believes that profiling is an ineffective approach to screening and security. The Behavior Detection Program is based exclusively on behaviors, not appearances. We believe that racial profiling is ineffective at best, un-American at worst and the agency does not condone, yet alone support, profiling of any kind.

    One need look no further than the thousands of arrests the behavior detection program has generated to know its effectiveness. This includes a man with pipe bomb components in Orlando, an accused double murderer in Minneapolis and countless drug smugglers, money launderers and all around criminals. While some may ask why TSA cares about the above (minus the guy with the bomb parts) it’s critical to know that the behaviors these individuals exhibit are identical to those we expect to see from a terrorist.

    Beyond the academic studies and high-profile incidents above, we are acutely aware that terrorist groups are interested in radicalizing individuals that do not fit any profile. These include well known terrorists Jose Padilla, Adam Gadahan and others. We should also not forget home-grown terrorist Timothy McVeigh.

    Christopher White
    TSA Public Affairs

  • Kin


    “Do the maths and you’ll figure out”

    Bush is offering security tips now?

  • James

    “Maths” is the accepted abbreviation of mathematics in Australia, New Zealand, and the UK. They also say things “al-you-min-ee-um” “spanner”, and “wanker”

  • Danorock

    Profiling of any sort is inherently “-ist” (racist, classist, sexist, etc.) but has been adopted as a security measure. Of course there have been good stoppages because of all of the extra TSA security and checkpoints, but it is doubtful that targeting any one racial or ethnic group will be the answer to all of our security problems. TSA employs behavior detection specialists who are supposed to evaluate your behavior in and around the gates to see if your actions give clues to a plan to smuggle or worse. It would seem that they could spend less time telling mothers and 90 year olds to dump out their precious formula/breast milk and ensure shakes, stop interviewing anyone with dark skin and an accent, and cut down the number of salaries that they are paying. In place of this exorbitant sum, they could increase their technological capability to detect explosives, x-ray, and scent recognition, coupled with facial recognition software. Sounds like a plan, no?

  • Hector Payne

    Let’s be honest here folks. We f*cking love nerds!

  • Just me

    Hmmm, so why does a short notice one way ticket automatically trigger a secondary inspection?

    If anyone buys a no notice or short notice one way ticket, you will be stopped at the gate EVERY TIME. TSA needs to stop this crap, and to say they do not profile.

    Quit profiling ticket purchases. If your airline boarding pass has a bunch of letters printed on the bottom, be ready to get stopped. That is their way of flagging the passenger.

    I put this here in an effort to get TSA to change their ways. Any moron will can figure out what is going on just by taking to flights the in the same manner. Terrorist do not just go in blind. They run a couple of dry runs, including taking the actual flighjts. We do not want another 9/11. Make the changes to improve our security.

  • Tommy

    Once again, the “eggheads” get it wrong. What works is not racial profiling but total profiling. Numerous things are considered. Actions, culture, area of travel etc. Based upon the primary profile, additional attention is given to that individual. This would be done with level one screening, level two, three etc. This minimises wasting resources on the 99.99% of air travelers.


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