To get a good idea of TSA's efficiency, lacking pre-TSA data, we could try to calculate the number of credible threat to a flight (gun ok, because they can discharge, since visibly their owner is prone to forget important things, but microscopic pointy objects that can be found inside a plane, no) caught at an airport, divide it by the total cost of screening, divide it again per pax, and calculate the same ratio for other countries. The system with the lowest dollar spent/incident/pax is the most efficient.

If you don't think people should be forbidden to carry a gun in an airplane, another calculation is possible. To discount the case of forgetful pax who happen to carry their gun on them, let's not take into account the case where people were not prosecuted with criminal charges after the gun was found. If it was only a mistake, they were just fined, apparently. So calculate the number of charged pax divided by total pax divided by the amount paid.

Then again, I suck at statistics.