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"5 Whys" Root Cause Analysis: Solving Causes, Not Symptoms

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I am a trainer and consultant in Lean Manufacturing, Six Sigma, quality management, and business management.

Why 5 Whys?

"Five Whys" root cause analysis is a powerful but very simple tool to identify the root of a problem so that you can treat the cause rather than just apply a band-aid—and it's applicable not just to businesses, but to any walk of life. Far too often, we tend to address the symptoms of a problem rather than addressing what started it in the first place. Stop wasting your time asking why a problem happened again and applying plaster for a temporary quick fix; use the Five Whys will help you to pull it up at the root.

Root cause analysis using 5 Whys

Root cause analysis using 5 Whys

Symptoms vs. Root Cause

When something goes wrong, we typically see the symptoms of the problem: the defects at the end of our production line or the failed machine. The cause of the problem is not always so obvious, and far too often, we jump to conclusions regarding what those causes are. We typically grab at another symptom of the original problem as being the root cause because we don’t investigate “deep” enough.

For instance, a teenager may blame their oily skin for their spots and buy many lotions and creams to cure the oily skin, but why have they got oily skin? The root cause could be down to their environment, their diet, or even their hormones or genetics. They are only tackling a symptom of the underlying problem, so they will never truly cure the issue.

Root cause analysis using the Five Whys will help your drive continuous business improvement and even improvements in other areas of your life.

History of the 5 Whys

The Five Whys originated within the Toyota Production System and are an integral part of Lean Manufacturing, Kaizen, and even Six Sigma. Taiichi Ohno saw the Five Whys as a very important part of Toyota's overall philosophy.

The Method

Like that annoying kid that keeps asking “why” when you give him an answer until you get to the point of just saying “because” when you run out of steam, Five Whys is a very simple method to use to drill down through the layers of symptoms to get to the root cause.

The process is simple: Just ask why five times in succession to get to the true root cause of the problem, as per the pictures below.

This is a very simple process, indeed, but more often than not, we stop at the very first "why" and try to do something about the symptoms rather than getting to the true root causes. Putting repeated sticking plasters onto our processes, we find ourselves having to deal with the same problems day after day and never make progress to actually solving our issues. This is why the Five Whys are so important and should be a discipline that is instilled at all levels within the organization.

Criticisms of 5 Whys

The criticisms of Five Whys are many, but to be honest, they miss the point. The idea of the Five Whys is not just to ask five questions, but to instill the discipline of searching for the true root cause behind something.

Stopping Too Early

In the example above we could still continue asking why a sixth or even seventh time, and investigate the maintenance routine of the machine, and so forth. The point is not to stop at five "whys." Five is typically enough to reach the true root cause; however, there will often be occasions when you need to ask six, seven, or even eight times to reach the true root cause. The point is to keep investigating to the point that you tackle the real cause.

Different People Come Up With Different Whys

The other problem is that when different people follow the process, they may come up with different "whys." Sometimes there are multiple symptoms and causes of a problem, especially with more complex problems. At this point, we try brainstorming and fishbone diagrams to try to determine the root causes, but again, we need to question each potential root cause to see if it is truly the root cause.

But if there is more than one potential root cause of a problem, don't just solve the root cause that caused today's problem. How many times do you see something that could go wrong and ignore it because you are too busy, only to have it bite you a day or a week later?

The Strength of the Technique

It is the discipline of searching for the root cause instead of tackling the symptoms that are the strength of the Five Whys technique; it is not meant to be taken as a literal five-step tool for individuals to use to get to the root cause every time. Use as many whys as you need to get to your root cause and if it means exploring more than one potential root cause, do so.

Continuous Improvement

In business, it is not enough to wait for a problem to occur and then tackle that problem. If you want to succeed, then you have to have a planned process of continuous process improvement. Five Whys is a very good tool and discipline to instill in your people, but it must be used within a planned framework of improvement.

You should consider implementing any findings you derive from using Five Whys across other similar processes also. If a lack of maintenance is causing problems on one machine, the chances are that it is causing problems elsewhere also. If one department’s skills with customer communication are causing issues with delivery, what communication issues are causing problems in other departments?

Improvement never ends if you want to succeed!

Quality Tools

In addition to Five Whys root cause analysis, there are a host of other quality tools that can help you with your continuous process improvement and help you to eliminate the true root causes of your problems;

Like many other quality tools, the Five Whys strategy is best used in conjunction with other techniques and as part of a planned process of improvement, not just in firefighting your daily problems. Used together, quality tools, including the Five Whys, are an effective way to improve your business and its competitiveness.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


Maria on October 04, 2019:

Great post!

I use 5 Whys iOS app to track the train of my thought on the way to the solution. It's also cool that app allows any number of questions.

I'm also keen on the Theory of constraints, and was happy to find an app called Bottleneck that now optimizes my to-do list and helps to focus on the most important tasks that limit the whole system.

I highly recommend 5 Whys and Theory of Constraints for all work or life matters you may have.

iyer s sankaranarayanan on January 13, 2018:

Excellent material. Very useful