5 Whys

The 5 Whys Technique is an iterative interrogative problem framing/solving method used to explore the cause-and-effect relationships underlying a particular problem. This technique was originally developped in the 1930's by Sakichi Toyoda, founder of Toyota industries.

It is a simple method that helps identifying the root cause(s) of a problem by repeating the question "Why?". Each answer consists in the basis of the next question. Even if the name of the technique is "5 Whys", you can repeat the question as many times as you need to acheive to the root cause of the problem.

Sometimes, problems have more than a single root cause. In this case, the method must be repeated asking a different sequence of questions each time. 

You know that you are at the end of the process when everyone is in agreement that the problem’s root cause is identified



Who is this tool for ? When should the tool be used?

City practitioners in charge of multi-stakeholder groups

Local stakeholders

It should be used at the beginning of the project in order to get a clear understanding of the problem and can be repeated several times during the project cycle if needed.

It should be used after the 4Ws tool.