The 5 x Why Method (The 5 Whys)

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Ger de Waard
Management Consultant, Netherlands

The 5 x Why Method (The 5 Whys)

The "5 x why" method has been developed by Toyota to perform an iterative Root Cause Analysis of production-related problems. The "5 x why" method is one of the available tools for performing a root-cause analysis. Its simple design and effective output made the 5 x why method also into a popular method used in Kaizen, Lean Production, Six Sigma, Value Stream Analysis, etc.

  • IDENTIFY THE PROBLEM for which the root cause has to be identified.
  • ASK: WHY has this problem arisen? The result is a reply with a new or different problem.
  • KEEP ASKING: WHY? Take the first answer (or problem) and reformulate the question: Where has this issue has arisen? Repeat these steps until you arrive at the core (root-cause) of the issue/problem.
The 5 x Whys can be used for several things:
  • VALIDATING ASSUMPTIONS: It is a simple tool that helps the Belt to unearth an assumption embedded in the process he/she is investigating. Once an assumption is revealed and of course also tested with data, it ensures excellent results.
  • DETERMINING ROOT CAUSES: However 5 x Why is more used in determining the Root Cause(s) of problems
    This technique is most used in the Analyze phase of DMAIC (Define, Measure, Analyze, Improve, Control). The 5 x Whys doesn’t involve a statistical hypothesis and in many cases can be completed without a data collection plan.
  • FINDING NON-VALUE ADD ACTIVITIES: The 5 Whys can also be used as a tool in Value Stream Analysis. Value stream mapping is as we know hard work because it requires looking at a process as if every step is non-value-added and is costing the organization time and resources. The 5 Whys is an easy way to root out as many non-value-added steps as possible.
Often you need to ask 6, 7 and even sometimes 8 x Why to find the real root cause of the problem. Perhaps a better name would be "Multiple Why’s Method".

An excellent example of 5 x Why is the Jefferson Memorial by Juran Institute.

  Ashok Kella
Manager, India

Our Endorsement to the 5 Whys

Yes, recently, in a complex issue dissecting in ou (...)

  David Week
Director, Australia

Better, but not 'root'

Five Whys is a great way to get better answers, bu (...)

  Ivan Kohlinsky
Management Consultant, United Kingdom

Back to Fundamental Thinking

Excuse me, but I am asking myself WHY is this meth (...)

  Dr. Schoenborn
Management Consultant, Germany

5-W in Combination with Impact Measurement

I agree with @David that 5-W is a good approach fo (...)

  Wulf-Dieter Krueger
Teacher, Thailand

5 Times Why - the Emperor's New Clothes

Watch your children asking this question again and (...)

Lecturer, India

Root Cause by Conscious Approach

A rational approach is certainly a way to get clar (...)

  David Torres
Manager, Mexico

5 x WHY’S is not Enough for Me

I took an 8D’s course and the homework was to take (...)

  Johnny Michael Tan
Management Consultant, Malaysia

I Prefer the Following Name for this Tool: Why-Why Analysis

I want to share that when my Semiconductor manufac (...)

  Rodolfo Dionisi

Tools According to Problem Complexity

Remember that the first step to solve a problem (o (...)

Lecturer, India

Role of Biases in Determining the 5 Whys

The 5 Whys as a tool is available for long and is (...)

HR Consultant, Belgium

1 WHY is Enough Sometimes

@Srinivas: There is always a WHY... Why this situa (...)

  Pedro Monteiro
Manager, Portugal

5 Why is Excellent Tool to Start and Get Back to the Basics

5 Whys is one of the best, simple and effective pr (...)

Lecturer, India

Preparing for Usage of 5 Whys

Before we use the 5 Whys is it possible and useful (...)


You Can Use 1 Why or 5 Whys or Multiple Whys

Not all people can solve a particular problem with (...)

  Ashok Kella
Manager, India

Change 5 Why into Why-why Analysis

@Johnny Michael Tan: I agree with you that "Five" (...)

  Dietmar W. Sokowski
Consultant, United States

Back to Fundamental Thinking

@Ivan Kohlinsky: Good point Ivan. Your comment is (...)

  Sudheendra G. Mudikeri
Management Consultant, India

A Tip for this Fundamental Why-Why Technique

No matter how many WHYs are used, this tool has wi (...)

  Olaf de Hemmer
Business Consultant, France

Why? or: What For?

I agree with pointing out that 'root cause' is hel (...)

  C.L. Kappagomtula
Professor, Malaysia

Even a Single 'why' Can Suffice, Without Overtly Asking 'Why'

Those of you working in production/operations migh (...)

  Miguel Sacramento
Business Consultant, Brazil

5 Why is not Japanese

@Wulf-Dieter Krueger: Yes. Every children has a "m (...)

  Bevis Qiu

Find the Most Cost-Effective Solution after 5 Whys

Different solutions can be found through different (...)

  Olaf de Hemmer
Business Consultant, France

Children Ask Why? Meaning what For?

@Wulf-Dieter Krueger: Are chidren not more interes (...)

  Miguel Sacramento
Business Consultant, Brazil

5 Why is not Japanese

@Olaf de Hemmer: Sometimes yes. It depends on each (...)

  Wulf-Dieter Krueger
Teacher, Thailand

Children Asking Why

Children ask why for the same reason as anybody el (...)

Manager, Nigeria

5 WHY Methodology is Advanced

The 5 WHY methodology for problem solving is more (...)

  Ashok Kella
Manager, India

Advanced 5 WHY Methodology

@FASESIN David: The effectiveness of Why-Why has b (...)

Lecturer, India

Organisation Service or Product Delivery - Human Analogy-Root Cause

When we considering an organization as a living be (...)

  jorge anibal hoyos hoyos
Manager, Colombia

Ask as Many Whys as Necessary

When talking about WHYS I also recall my kids when (...)

Lecturer, India

Conscious Approach

We have expert systems which are currently under d (...)


Methods of Iterative Root Cause Analysis

We have a lot of tools available in the past and a (...)

  Lee, Youngki
Consultant, Korea (South)

My Important Experience with 5 Whys

I engaged a company in a training meeting with emp (...)

Lecturer, India

Delegation of All Rationally Viable Methods

If all rational methods including why why approach (...)

  Olaf de Hemmer
Business Consultant, France

AI and Causes / Goals

@Srinivas: I'd be curious to see how AI gets the a (...)

Lecturer, India

Feedback Loop Mechanism

Using semantic web technologies which are based on (...)

  C.L. Kappagomtula
Professor, Malaysia

Stochastic Approach to Root Cause Analysis May Be the Need of the Day

I fully concur with Ger De Waard's argument to not (...)

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