5 Whys Root Cause Analysis (Toyoda)

5 whys analysis toyoda - Toolshero

5 Whys Root Cause Analysis: this article explains the 5 Whys Root Cause Analysis, or 5 Whys Technique, developed by continuous improvement guru Sakichi Toyoda in a practical way. It covers an introduction to the method, the application and an example. After reading you will understand the basics of this powerful root cause analysis and problem solving tool.

Introduction of the 5 whys process analysis

Although problems are not welcome in any organization, they appear in organizations of all kinds. For every problem there is a solution and problems are a reason to start up improvement projects.

But what is the best method to find effective solutions? Effective solutions can only be found by searching for the root cause in a structured and controlled manner, for instance using the 5 whys analysis.

Free Toolshero ebook

Root cause of the problem

By looking for the root cause of the problem (a root cause analysis), repetition of the problem can be prevented.

The problem has to be nipped in the bud. When problems are dealt with systematically, an organization and individual team members can find the root cause of the problem and deal with this effectively.

5 whys analysis

In the Japanese 5 whys exercise analysis the question ‘why’ is asked five times.

The 5 whys analysis was originally developed by Sakichi Toyoda, and was used to reach the root cause of the problems within the manufacturing process of Toyota Motors.

Today, the 5 whys analysis is frequently used within LEAN Manufacturing, Gemba Kaizen and Six Sigma.

This 5 whys analysis makes it relatively simple to identify the root cause of the problem. The problem-solving journey starts with a clear formulation of what exactly is going on. Therefore, the firs step is to define the problem.

Once the root cause has been identified in a problem statement, there is no more need for the ‘why’ questions. The root cause is often closely associated with previously identified parts of the initial problem. Corrective actions can now be taken.

Example of the 5 Whys Root Cause Analysis

A garage business is dealing with a bad delivery of car tyres. Normally, the delivery takes place within 24 hours, but the delays are now running up to three working days.

The garage runs the risk that customers will use the services of another garage that can fit their new tyres within 24 hours. The quality department of the garage business decides to start up an expensive checking system to prevent delays. Transport company G is also involved in this process.

Eventually, the transport company decides to search for the root cause of the problem using the 5 whys analysis.

  1. Not able to deliver tyres within 24 hours – Why?
  2. Supplier has insufficient stock – Why?
  3. Supplier depends on exporter; cargo boats are delayed – Why?
  4. The cargo boats are waiting for freight to fill op their holds – Why?
  5. In times of crisis freight boats get fewer orders and therefore collect different freights that can be transported in one journey – Why?

This is how the root cause of the problem is identified and it enables a company to find a solution. The solution cannot be provided by the transport company or the supplier.

The crisis is the cause for the fact that freight boats wait until their holds are filled before they leave port. The garage can now try and find another (temporary) solution with the supplier and consider buying the tyres somewhere else.

Repeating why five times

The strength of the 5 whys analysis lies in the repetition of the question. This prevents that people start from assumptions and classic root causes of problems such as lack of time, lack of money and manpower shortage. Naturally, these factors might be causes too.

By repeating the ‘why’ question, people are forced to identify different causes that may be responsible for the problem. In order to look for the cause more specifically, the ‘why’ question can be extended with for example asking the question ‘why has the process failed’.

People are inclined to stop looking for a cause when the cause of the problem has been identified. However, it is important to remain alert and ask the ‘why’ question repeatedly so that causes can be identified at different levels.

Join the Toolshero community

Now It’s Your Turn

What do you think? Is the 5 whys analysis still applicable in today’s modern companies? Have you ever used this method to get to the nature of the problem? Do you recognize the practical explanation or do you have more additions? What are your success factors for the good 5 whys analysis? Do you know scientific approaches to problem solving?

Share your experience and knowledge in the comments box below.

More information

  1. Becker, R. M. (1998). Lean manufacturing and the Toyota production system. Encyclopedia of World Biography.
  2. Feld, W. M. (2002). Lean manufacturing: tools, techniques, and how to use them. CRC Press.
  3. Martin, J. (2006). Lean six sigma for supply chain management. McGraw Hill Professional.
  4. Motwani, J. (2003). A business process change framework for examining lean manufacturing: a case study. Industrial Management & Data Systems, 103(5), 339-346.

How to cite this article:
Mulder, P. (2012). 5 Whys Root Cause Analysis (Toyoda). Retrieved [insert date] from Toolshero: https://www.toolshero.com/problem-solving/5-whys-analysis/

Original publication date: 09/19/2012 | Last update: 11/02/2023

Add a link to this page on your website:
<a href=”https://www.toolshero.com/problem-solving/5-whys-analysis/”>Toolshero: 5 Whys Root Cause Analysis (Toyoda)</a>

Did you find this article interesting?

Your rating is more than welcome or share this article via Social media!

Average rating 5 / 5. Vote count: 11

No votes so far! Be the first to rate this post.

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Patty Mulder
Article by:

Patty Mulder

Patty Mulder is an Dutch expert on Management Skills, Personal Effectiveness and Business Communication. She is also a Content writer, Business Coach and Company Trainer and lives in the Netherlands (Europe).
Note: all her articles are written in Dutch and we translated her articles to English!


One response to “5 Whys Root Cause Analysis (Toyoda)”

  1. Kathy Castle says:

    Thank you for sharing.

Leave a Reply