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Five times Why Root cause analysis

The Five times why is a straightforward methodology that explores the underlying cause and effect of particular problems. The primary goal is to determine the root cause of a defect or a problem by successively asking the question “Why?”.

Simply put: Start by stating the problem, and then ask Why?.
For the answer, you come up with, ask Why? again.

Repeat this process five times, or as often as possible. The final answer comes closest to the heart of the problem and is therefore called the root cause of your problem. 

The root cause often relates to a particular problem or the lack of a particular process. When you solve the root cause you can prevent the problem from reoccurring.

Example

Problem

Peter almost got hit by a forklift.

Five times why

  1. Why did Peter almost got hit by a forklift?
    Answer: Because he walked off the pavement.
  2. Why did Peter walk off the pavement?
    Answer: Because pallets were blocking the pavement.
  3. Why were pallets blocking the pavement?
    Answer: Because there were old markings on the street; the operator who put the pallets there was new so he didn't know this spot wasn't used anymore
  4. Why were there old markings on the street?
    Answer: Our Technical Service forgot to remove the old markings.
  5. Why did our Technical Service forget to remove the old markings?
    Answer: Markings are supposed to be logged; there is no procedure in place for how and how often the log file should be updated.

So in this example, there is no procedure for updating the log file on markings. If such a procedure is agreed upon and respected, the chance of erroneous markings becomes much smaller.