TSA: Like burglar alarms?

Bear with me on this one…

Among the many thoughts I’ve been having on the TSA’s controversial backscatter “strip search” scanners are some musings based in game theory. Let’s look at the “players” in the security game:

  • TSA: Chartered with securing air travel. Strongly motivated to avoid the possibility of blame being assigned to them when a terrorist event occurs.
  • Politicians: Want to be re-elected. Subject to the whims of the polls; right now that means being “tough of terrorists”. Current controversies may swing some politicians away from the “security at any cost” mindset.
  • Pilots/Crew: Concerned with balancing security against their own personal well being and effectiveness as employees.
  • Flyers: Want to be safe, but there are threshold costs for security which won’t be acceptable. Where those thresholds are is subject to some debate.
  • Non-flying public: Insulated from any costs (economic, political, mental, social, etc.) of flying security measures. Hard to uniformly classify motivation as a single group.
  • Terrorists: Want to disrupt American lifestyle sufficiently to achieve their goal (remove US from Middle East/undermine support for Israel/support Sharia law in homeland/influence domestic US politics and laws towards Islam/whatever).

Some interesting features of the game:

One thing that clearly strikes me is that the interests of TSA do not align with the interests of the Pilots/Crew or the Flyers. TSA has no interest in assuming a “compromise” or “balanced” security policy. TSA only wants one thing from both groups – unquestioning compliance. I think this conjecture from the game bears out in the reported demeanor of TSA in real life.

Non-flying public is numerically larger than the flying public. Politicians are influenced by these two groups, but because the Non-flying Public doesn’t bear any direct costs to security, it is natural for the Politicians to under-value to the cost imposed on the Flyers group. The Politicians exert influence on the TSA. So the combination of the TSA having no incentive to decrease costs of security and the Politicians under-valuing costs of security implies that the feedback loop that should limit and control security policy to a reasonable level is actually weak and likely to result in over-costly security policy.

In the “mini-game” of a Terrorist attack, it’s not necessary for the attack to succeed in order for it to benefit the goals of the Terrorists. This means that it’s actually possible for a failed terror attack to be viewed as “positive outcome” to both the TSA and the Terrorists. The TSA because they can claim success and justification for their security measures. The Terrorists can as well, as long as the attack foments alarmist media and political coverage and results in increased fear.

Another striking feature of our “game” is that Terrorists and TSA are not diametrically opposed to each other. It’s possible for TSA and Terrorists to both “win” (or at least, both not lose) assuming the Terrorists can find a way to disrupt America that doesn’t depend on attacking the airline industry. Here at last is the feature of the game that inspires my title! Economics and game theory say that a burglary alarm doesn’t necessarily prevent all burglaries, it only has to prevent burglaries against the homeowner who pays for it. If it causes burglaries to shift to adjacent homes, there is a benefit to the alarmed homeowner, but a consequent loss to the neighbors. TSA is, in effect, like a burglar alarm – it encourages Terrorists to attack other targets. As long as the targets aren’t aviation related, TSA “wins” their part of the game. Of course, the problem is that the actions TSA takes to win are not necessarily the best for the public at large.

Just a few quick concrete examples of why this feature of the game should be so worrisome:

  • Security spending is limited to a finite budget. Ideally we should optimize our security budget over all policies and activities to result in the best security possible. Or, in the terms of our game, we should optimize our security spending so the Terrorists get as low a score as possible in the game. TSA (and all other single-scoped security agencies) are not motivated to do that. They are motivated to increase their security budget as greedily as possible in order to maximize their chances of securing their sector in the game, regardless of how cost-effective any given policy is.
  • Shifting behavior and secondary effects may impose costs higher than the Terrorists. For example, driving is much more dangerous than flying. Every time someone decides to drive instead of fly a long distance, we are increasing the number of deaths and injuries suffered on the roads. Since the death and injury rate from Terrorists is so very low, it doesn’t take many additional deaths to negate the benefits of enhancing aviation security.

The secondary health losses are one of the big controversies over the backscatter x-ray searches, and are also a perfect example of the second point. Even though the health risk is likely minuscule from a single scan, if the scanners are widely used on a significant percentage of fliers, the minuscule health impacts accumulate into being more damaging than the Terrorists. Since terror attacks are such a highly improbable event, even scanners that sound very very safe in the context of a single scan could easily accumulate a negative impact that outweighs any benefit to stopping Terrorists.

I’d love to see a more detailed analysis of this game, but from just my cursory knowledge of game theory it’s obvious to me that the flying public must 1) become very vocal about the costs of the TSA policies and 2) gain support from the non-flying public. Only then can we muster enough influence on Politicians to push through and influence the TSA.

If you agree, I encourage you to write or call Congress, talk to your friends and family about why you disagree with TSA policies, and, if you’re flying, opt out of the invasive body scanners. You’ll be subjected to an invasive “enhanced pat-down” as a result. I would encourage you to complain to your Congressional representatives as well as the ACLU if you feel that the TSA policy is inappropriate.

If you’re interested in a huge collection of links related to the TSA policy situation, please check out this post from Bruce Schneier: TSA Backscatter X-ray Backlash.