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The Power of “Five-Whys”

March 4, 2010

The “Five Whys” is a technique used in the Analyze phase of the Six Sigma DMAIC methodology. The “Five Whys” is a great Six Sigma tool that doesn’t involve a statistical hypothesis and in many cases can be completed without a data collection plan.  (

I have talked about the “Five-Whys” technique in some of my classes.  It is an excellent technique for root cause analysis.  It can take you from surface symptoms to underlying cause.  The “Five-Whys” is useful because of the following reasons:

The“Five-Whys” are particularly useful in situations that involve human factors or interactions.  They can be used outside of the Six Sigma context.

The term “Five-Whys” is not intended as a literal term. A team might need more or less than five whys to tunnel down to the root cause of a problem.  When starting the process, it is important not “lead” the questioning to a preconceived “why.” (

While the “Five-Whys” is a very useful tool, it does have some limitations.  The brainstorming storming required to do “Five-Whys” is time-consuming when compared to other methods.  This method can be particularly arduous for larger groups.

The results garnered from the brainstorming used in the “Five-Whys” technique may vary according to group and are difficult to reproduce.  Even after the process has been followed, the root causes may not be identified. There is no means to verify that the root causes were identified. (

This post is laced with excellent resources and I have provided a link to a template that is helpful to use with this technique.

5 Whys Template

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