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Root cause analysis techniques September 28, 2007

Posted by Coolguy in Six Sigma.
Tags: , ,

5 Why Technique

Simplest technique to indentify the root cause of a problem. You ask “Why ?” for 5 times (can vary) to get to the bottom of a problem. When you have answer to a question, you can frame the answer into another “Why” Question. Its one of the most simplest techniques to identify a root for a problem. For this technique to work, questions should be concise and focussed. Its effective for solving problems involving human factors.

Fish Bone Analysis (Ishikawa Diagram)

Can be used when you have a complex problem having multiple causes and when you need to brainstorm to identify possible causes. First step is to frame a Why question stating the problem and place it at the head. Draw a horizontal line leading to the head and vertical lines leading to the main line. Label vertical lines with categories or departments where the problem may have originated.

Some standard categories for service industries are : Policies, procedures, people and strategies.

Three steps to complete a fishbone are:

  1. Brainstorming
  2. Prioritizing
  3. Action plans

4M version of the plan has Manpower, Material, Method, Machine. 5M and E has measurement and Environment exra.



1. Sutton Burleigh - April 2, 2008

I can’t agree more. I believe most people jump to conclusions and don’t get to the root cause which of course is the basis for continuous improvement. Simply asking why gets to the base.

The fishbone is a great tool to weed out causes and get a project team aligned.


2. Sutton Burleigh - April 2, 2008

To add to that; in my experience a cause and effect matrix can also supplement the use of a fishbone.

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