Random selection vs profiling at airport security checkpoint

The question of how to select people for extra security check has been discussed at length by people, who like me know very little about security. Usually it was a choice between random selection that was considered morally superior and profiling (read “racial profiling”) that was thought efficient but morally questionable. It was always a consensus that profiling was more efficient than random selection.

I used to be convinced as well - until last night when a friend remarked: "Anybody could be sneaking a bomb for the terrorists". Immediately, it dawned on me that she was right - given any type of profiling in action, terrorists have a very strong incentive to have somebody with the lowest probability of being inspected to sneak the bomb through the checkpoint. It can be a member of their group or an outsider - bribed, threatened, or deceived. The point is that if terrorists can observe profiling in action they can deduce the best way around it.

So being tremendously inefficient and costly in absolute terms, random selection is the only unbeatable strategy when you fight organizations that can spend enough resources to study your profiling strategy and choose a person that surely passes.

Let me finally add a little economic twist to the idea. To perfect the strategy, I would still add some tiny part of racial profiling bias to the mostly random selection at the security checkpoint. The idea is that terrorists have to either sneak the bomb themselves or have to incur additional expense in risk and possibly money to have somebody in the low risk group do it for them. If the selection at the checkpoint is purely random, they can save the expense by doing the sneaking themselves. The tiny racial bias should add just enough risk for people with the terrorist racial profile to make an average terrorist group indifferent between doing the sneaking themselves and having somebody else do it for them. Now, even though the terrorists can be fully aware of our strategy, they can do nothing to minimize their risk. This is the best, I am afraid, we can do with our knowledge of terrorist’s racial profile in this simple model.