5 Whys analysis

5 whys tool by Sakichi Toyoda - problem solving tool - ToolsHero

5 Whys: this article explains the 5 whys analysis, developed by continuous improvement guru Sakichi Toyoda in a practical way. After reading you will understand the basics of this powerful root cause analysis and problem solving tool.

Introduction of the 5 whys 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.

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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 can find the root cause of the problem and deal with this effectively.

5 whys analysis

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

The 5 whys analysis was originally developed by Sakichi Toyoda, and was used to trace 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 find out what the real root cause of the problem is. The problem-solving journey starts with a clear formulation of what exactly is going on.

Once the root cause has been identified, there is no more need for the ‘why’ questions. The root cause is often closely associated with previously identified parts of the problem.

Example of the 5 whys 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.


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.

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Now It’s Your Turn

What do you think? Is the 5 whys analysis still applicable in today’s modern companies? Do you recognize the practical explanation or do you have more additions? What are your success factors for the good 5 whys analysis?

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 analysis. Retrieved [insert date] from Toolshero: https://www.toolshero.com/problem-solving/5-whys-analysis/

Published on: 09/19/2012 | Last update: 02/17/2022

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One response to “5 Whys analysis”

  1. Kathy Castle says:

    Thank you for sharing.

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