to MGAHAN:
"...by asking a number of selected questions..."
In my opinion, here is the main problem. Who is going to ask them? Live person or computer?
If you use a computer, then you need a question bank (it may be secret or available to anyone, that's another story).
If you use live examinator to test your candidates, then you run into the problem of personal judgement. Every teacher has at least several questions, which are very difficult to answer. And every examinator can make your life very difficult on the exam. Yes, normally examinators are reasonable people, but every rule has an exception. You said you are from younger generation... now imagine being tested by 70-years old guy, who seems not to like you from the moment he saw you :-)