Best to use when
Five whys should be used to get to the very root of a reasons for a problem. It also shows the relationships between several causes of the problem.
Write down a specific problem.
Ask the team to individually write down why that is happening.
Form a new problem from the answers the team gave.
Repeat steps 2 and 3 four more times or as much as necessary.
Analyze the results and form relationships between answers.
- The vehicle will not start. (the problem)
- Why? - The battery is dead. (first why)
- Why? - The alternator is not functioning. (second why)
- Why? - The alternator belt has broken. (third why)
- Why? - The alternator belt was well beyond its useful service life and not replaced. (fourth why)
- Why? - The vehicle was not maintained according to the recommended service schedule. (fifth why, a root cause)