Finding root causes with 5-Whys – MES009

Root cause? What’s that?

Remember your last sickness. Caught a cold or a flew? Weren’t you only curing the symptoms? Usually nobody cares for the real reasons when getting ill with these small diseases. But there are lots of persons who are able to somehow avoid any disease. What’s the difference? Why were you felt sick?

It’s like weeding your garden. Very often only the symptoms are cured, but no real solution can be achieved. The weed gets back soon. Removing the root would do the job,
but that costs additional effort, back-pain and time.

Within the business context regularly the management requests an immediate, complete, fast and reliable solution of problems. But is that possible without finding the real cause of a problem? Without fixing the real cause of a problem it might pop the same way again as the weed does.

That’s the ideas of root cause analysis. Dive deeper into a problem to find the real underlying cause of the problem. The diving should be that deep to find not only a cause, but the process which is failing or is insufficient

This episode is about the first and basic technique of finding the real root cause of a problem: the 5-Whys technique

5-Whys to find the root cause

The 5-Whys is a technique first time introduced by Toyota within the Toyota Production System (TPS). It is an iterative question-asking technique to explore the cause-and-effect relationship underlying a particular problem.

The technique belongs to repeating the question “Why?”. Each question forms the basics of the next question. The “5” in the name derives from an empirical observation on the number of iterations, which is typically required to find the real cause of a problem – the root cause.

The idea of 5-Whys is to dig deeper. But it’s even more. It not only stupidly asking Why, Why, Why again and again. It’s a change in the paradigm of evaluating the cause of a problem by not getting stucked with the symptoms. It’s like unveiling an onion. You work from one shell to the other until you come to the nucleus.

Benefits of 5-Whys

The 5-Whys technique has several benefits:

  • It helps to identify the real cause of a problem
  • It uses small incremental steps to improve the situation
  • It is one of the simplest tools; it’s easy to complete without any statistical analysis
  • It also determins the relationship between different root causes of a problem

The 5-Whys is most useful for problems involving human factors and interactions, like handling, reactive, planning, or design problem. However complex problems might benefit from a more detailed approach. Hereby the 5-Whys can deliver useful insights.

Criticism of 5-Whys

The 5-Whys technique has several disadvantages and is under critique for:

  • its tendency for investigators to stop at symptoms rather than going on to lower-level root causes.
  • its inability to go beyond the investigator’s current knowledge. You will not find causes that you do not already know.
  • its lack of support to help investigators for asking the right “Why” questions.
  • its possibility to provide different results for the same analysis. Results are not repeatable. Different people using 5-Whys come up with different causes for the same problem.
  • its tendency to isolate a single root cause, whereas each question could elicit many differenr root causes.
  • its lack of supporting multiple reasons for a problem. You will have to decide to follow one path only.

How to 5-Whys

Nevertheless “5-Whys” is a great tool to start with the root-cause analysis. It is fast, in an elaborated hand very effective and therefore efficient in an outstanding way.

To improve your understanding of how to do the 5-Whys I have these 3 steps to follow:

Start the 5-Whys

Start with a description of the problem by providing answers on these questions:

  • What has happened?
  • Who was engaged?
  • When does it have happened?
  • Who has detected the problem?
  • What impact does the problem have?

Best thing first is to invite for a meeting to start the 5-Whys questioning

Do the 5-Whys

First you should define a 5-Whys master or moderator. This should be an elaborated person who is able to work on a meta-level of the outstanding communication. It should not be one of the major stakeholders, if he have the tendency to fell blamed for what has happened.

  1. Start with the first “Why” question
  2. Note the answer and validate it by reversing the statement and validating the statement. Example:
    Q: Why do I have forgotten my keys today morning?
    A: I have forgotten my keys because I was in a great hurry
    If I would have been not in a hurry today morning I would have not forgotten my keys? Right or False?
    That’s not a clear conclusion! That’s not the cause of having forgotten the keys.
  3. Check for additional causes. Eventually us a parallel path of investigation.
  4. Ask “Why again”
  5. After some iterations and you got the impression to be done change the question to “Why does our process have failed?”

Especially the last step is the most essential one. This changes your perspective from symptoms and easy causes towards a general view. This is the starting point of real improvement. Knowing the failed process is a cornerstone in becoming really better.

Report the results of 5-Whys

If you have digged out one or multiple root-causes for your problem, then summarize the results:

  • Provide the historical data
  • Highlight the priorities of the different problems (perhaps by using a Pareto-chart or similar)
  • Show the results of the 5-Whys
  • Provide first ideas of corrective actions and their verification

Pay attention

Please be aware that the 5-Whys are simple in concept but sometimes tricky in reality. The following 3 aspects are essential to keep an eye on:

  1. Many times teams will stop once a reason for a defect has been identified. These conclusions often do not get to the root cause. A disciplined 5-why approach will push teams to think outside the box and reach a root cause where the team can actually make a postive difference in the problem, instead of treating symptoms.
  2. Avoid intentional or unintentional bias while answering! Find the right person who can answer the 5Why’s! Use other RCA Tools if you’re getting misleading answers.
  3. Do not ask your coworkers again and again for the Why. Do not upset them.


5-Whys are living from experience and excercise. Don’t be impatient if the result is not that good in the first usage. Using it continuously will give you the expertise to do it quicker and more elegant. Don’t hesitate to improve!

Thank You For Listening

Out of all the podcasts available in the Internet you tuned into mine, and I’m grateful for that. If you enjoyed the episode, please share it by using the social media buttons you see at the bottom of this note. Also, I would be very happy if you would consider taking the minute it takes to leave an honest review or rating for the podcast on iTunes or Stitcher. They’re extremely helpful when it comes to the ranking of the podcast. For sure I read every single one of them personally! Or, if you prefer a more direct contact, don't hesitate and drop me a note at

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