5 Whys Blog

What are the 5 Whys & When is it Used in Six Sigma?

Five whys (or 5 whys) is a technique first described by Taiichi Ohno at Toyota Motor Corporation. It is an iterative interrogative technique employed within the six sigma methodology, and used typically to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem by repeating the question “Why?” five times. The answer to the fifth why should reveal the root cause of the problem. Below you’ll find an example of this.
An example of a problem is: the vehicle will not start.
Why? – The battery is dead.
Why? – The alternator is not functioning.
Why? – The alternator belt has broken.
Why? – The alternator belt was well beyond its useful service life and not replaced.
Why? – The vehicle was not maintained according to the recommended service schedule. (The root cause)
The questioning for this example could be taken further to a sixth, seventh, or higher level, but five iterations of asking why is generally sufficient to get to a root cause. The key is to encourage the trouble-shooter to avoid assumptions and logic traps and instead trace the chain of causality in direct increments from the effect through any layers of abstraction to a root cause that still has some connection to the original problem. In this example, the fifth “why” suggests a broken process or an alterable behaviour, which is indicative of reaching the root-cause level.
The last answer points to a process. This is one of the most important aspects in the five why approach – the real root cause should point toward a process that is not working well or does not exist. Untrained facilitators will often observe that answers seem to point towards classical answers such as not enough time, not enough investments, or not enough resources. These answers may be true, but they are out of our control. Therefore, instead of asking why?, ask why did the process fail?
The 5 Whys is just one of the many techniques you’ll learn in our IASSC six sigma courses at Hudson. It’s covered in significant depth within our six sigma black belt course through videos, notes, quizzes, and downloadable template.
Free sample
To help you better understand how six sigma can help your organisation, Hudson Courses have made available a 5 whys template from our IASSC six sigma course. This is just one of many templates offered within our six sigma courses to help you better understand the methodology and add value to your organisation.

Click the icon above to download your free six sigma black belt template sample from our IASSC six sigma course

A closing note
We hope you found this article helpful in understanding how six sigma can benefit your career and organisation. If you’re looking for further advice on getting IASSC six sigma certified, please feel free to reach out to the Hudson Courses support team. We’d be happy to answer any questions you have.

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