Hope I can test this while I still remember it, with something concrete that the technique get imprinted in my memory.
The 5 Whys is a question-asking method used to explore the cause/effect relationships underlying a particular problem. Ultimately, the goal of applying the 5 Whys method is to determine a root cause of a defect or problem.
The following example demonstrates the basic process:
* My car will not start. (the problem)
1. Why? – The battery is dead. (first why)
2. Why? – The alternator is not functioning. (second why)
3. Why? – The alternator belt has broken. (third why)
4. Why? – The alternator belt was well beyond its useful service life and has never been replaced. (fourth why)
5. Why? – I have not been maintaining my car according to the recommended service schedule. (fifth why, a root cause)
via 5 Whys – Wikipedia, the free encyclopedia.