a card with 'why' written on it, with an arrow to a second card with 'why' written on it

Exercise: Five Whys

Dig deep into the actual reasons for a problem.

Back to Understand

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)