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....
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.
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.
However, I would like to post an excerpt from the last link that I shared.
"TSA acknowledges that it takes 10-12 seconds per passenger to go through the scanner while only 2 seconds is needed for the metal detector. Since the scanners have a 54% false positive rate, approximately half of those using the scanners receive some form of pat-down, further slowing the process. When hundreds of people are in line, that additional 8 to 30 seconds each adds up, resulting in substantial delays.
So while TSA claims that the scanners speed up the screening process, the opposite, in fact, is true."