Statistical Sampling in Security

Use it if you are satisfied with "reasonable" security.

This happens figuratively all over the place (My apologies Mr. Saxena, just feeling mighty happy this Sunday)..

Security

You have to perform security per your countries regulations. You can't invent your own security procedures. The end destination country can place requirements on departure flights.

In the USA, the rules flow down from the Federal Code of Regulations, which puts requirements on the Transportation Security Administration (TSA). The TSA then has procedures that they can modify e.g. what you can carry on. Every carry on/checked bag gets X-rayed. All persons go through metal detectors.

So since your asking, you must be in a country that is giving you license to make your own security rules. Where is this?

A bomb on ground transportation has limited catastrophic outcome vs a loaded aircraft. You can not use that as any rational reason for aircraft security.

Follow the regulatory requirements of your country.

OP is talking about Metro travel. Underground trains. Subway.

I somehow missed that detail of "metro", and thought that he was using ground transport as rational for air travel.

What really sucks is that we used to live in a free society where terrorism was not a worry.

Yes right after a world war and a cold war. You maybe have been growing up in a quiet part of the world for a couple of years and now worlds end is catching up with you. You can call this century the Terror War century

Quantitative and qualitative approach are two different thing and cannot be used in the same sense.

"Your adversaries will always use the complement of your screening process..."

Absolutely spot on correct. Any weakness that can be identified will be exploited by anyone determined to defeat the system.

If a CD or DVD doesn't play, or a breadmaker doesn't make bread, the customer mutters, then returns the purchesed item and receives a replacement or a refund. If a machine-screw is badly threaded, and won't fit corrrectly, the operative mutters, then bins it and picks up another.

If a suicide bomber slips through the sampling, there will probably be any people killed.

Not quite on the same scale.

I think it unwise to do anything less than 100% screening for reasons mentioned by other posters. I also think the way the Israelis undertake this is really very clever. Talk to each passenger, gauge reactions, understand body language, and also use a "sniffer" to detect the smell of fear. If a dog can detect fear, humans eventually will get it. General profiling as to the type of character this usually represents may be helpful in funneling the "applicants" to the correct "reception" area.

Also, let the bad guys know that if they that if selected for the advanced probing, they will receive a pig lard suppository right before the chamber detonates their bomb vest.