As a concept, the 5 Whys is indeed easy to explain, and so naturally people are quick to start using it. But that is where people often go wrong. Just because it is easy to explain does not mean that it is easy to use … Correctly!
The architect of the Toyota Production System, Taiichi Ohno, described the 5 Whys as “the basis of Toyota’s scientific approach … By repeating why five times, the nature of the problem as well as its solution becomes clear”.
Indeed, 5 Whys is a seemingly straightforward technique. But I would argue that it is a myth that 5 Whys is an easy technique to use. Just because you keep asking “why”, does not mean that you will always get to the root cause of the problem. Or at least the “right” root cause. That has certainly been my own, rather painful, experience.
In order to know when and how to apply 5 Whys, it is critical to understand that the tool has certain limitations. Some are obvious, and some less so.
Those were some of the more obvious limitations to 5 Whys. Typically, users get wise to them after a couple of attempts at the technique. I certainly did.
That was some of the main limitations of the 5 Whys. The obvious, and not so obvious, limitations to which people often fall victim. Does this confirm that it is a myth that the 5 Whys is a straightforward root cause analysis technique? Maybe, maybe not. But what I can confirm is that I certainly wish that I had been aware of these limitations before I started using the technique.
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