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Re:TSA Out of Our Pants -- FAQ by mikeash on Sunday March 11, 2012 @09:56PM (#3692014)
54% is an astonishingly high number. Any idea what the false negative rate is? I wonder if the scanners are any better than just flipping a coin....
Re:TSA Out of Our Pants -- FAQ by newman314 on Monday March 12, 2012 @12:13AM (#3692306)
Well, a false positive rate of 54% essentially means it is in fact just coin flipping.

For any other product on the market, a failure rate of 54% would be cause for a complete recall if not a wholesale scrapping of the product but apparently does not apply in this case.

Re:TSA Out of Our Pants -- FAQ by mikeash on Monday March 12, 2012 @09:29AM (#3693397)
You need to know the false negative rate to evaluate it against a coin flip. For example, a hypothetical machine with a 50% false positive rate but 0% false negative rate could still be really useful, if the machine itself is cheap/fast and the subsequent screening slower/more expensive. With such a machine, you know that the 50% who pass are clean, thus reducing your followup screening load by half.

Of course, a machine with ~50% false positive and negative rates is indistinguishable from flipping a coin.