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Ishikawa Fishbone Diagram; Cause and Effect; Continuous Process Improvement

Updated on January 19, 2015
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I am a trainer and consultant in lean manufacturing, Six Sigma, quality management, and business management.

Continual Process Improvement Using Ishikawa Diagrams

The Fishbone diagram, Ishikawa diagram or even Cause and Effect diagram is an effective tool to help you visualize what is happening within a process and thus analyze data and help direct your team towards a solution to a problem.

No business can survive long term unless it improves over time, this is best done as a planned program of continuous process improvement with data collection, data analysis then solution selection and implementation.

The Ishikawa Diagram or fishbone Diagram as it is often known due to its resemblance to said skeletal arrangement uses its structure to organize your data under specific related topics helping you to better understand how things are related and help you to identify cause and effect.

This and other quality tools will help you to drive continuous process improvement within your organization, improve your profits and grow your business.

Continuous Process Improvement Fishbone Diagram

Ishikawa Diagram, Quality Tools
Ishikawa Diagram, Quality Tools | Source

Why Fishbone Diagram or Ishikawa Diagram

The fishbone diagram was invented by Kaoru Ishikawa to try to organize problems solving teams thinking, hence the name Ishikawa diagram after its inventor. The name Fishbone diagram of course being derived from its resemblance to the skeleton of a fish.

The Ishikawa or Fishbone diagram is a very effective tool for continuous process improvement that allows you to analyze and visualize a large amount of information.

Ishikawa Diagram Example

Fishbone Diagram Example
Fishbone Diagram Example | Source

Cause and Effect Diagram

Cause and Effect
Cause and Effect | Source

Cause and Effect

The main aim of the use of the Ishikawa Diagram is to identify and organize the potential causes of an effect. For example you may have conducted your data collection on your factory floor and found that the biggest reason for rejects in your molding shop is “short shots” of material. This Effect then is placed at the head of your fishbone diagram as the effect that your looking for potential causes for. The “bones” coming from each direction on the spine of the fishbone are where you organize your potential causes.

The potential causes normally being generated through a brainstorming exercise either directly onto the diagram or as a separate exercise that is then organized within the Fishbone Diagram framework.

4Ms, 5Ms, 6Ms

The bones coming from the main spine of the Ishikawa Diagram are usual named according to the 4, 5 or 6 Ms, depending on the complexity of the problem or the process that you are looking to improve.

The Four Ms are:

Manpower, the causes that can be attributed to the people working on the process, so things such as training would be placed on this arm of the diagram.

Methods, what is it about how we conduct the operation that can cause the effect that we are trying to solve such as machine setup process used.

Machines, the causes due to the machines or the equipment in the process, maybe you have more than one machine used for the process.

Materials, potential causes due to the materials used, such as the difference between two suppliers of the same material.

The 5th and 6th Ms are usually;

Mother Nature or the “M-vironment”, causes that are related to your surroundings such as external temperature or humidity.

Measurement or Metrics, Do we have causes that are more related to how we measure the process?

Cause and Effect Video

Analysis of your Fishbone or Ishikawa Diagram

A brainstorming session to generate potential causes can come up with many potential causes of the effect in question. The team has to then analyze the potential causes to decide where to focus their attention.

The first stage is to highlight those that causes that are likely to be the main contributing factors, an easy way to do this is rate each cause, depending on how detailed you want to be this can be as simple as hot, warm or cold or rating from 1 to 10. Myself I prefer just to use hot, warm or cold, you can spend too much time arguing over whether it is a 3 or a 4 rather than getting on with resolving the issues.

The next stage is to look at the remaining “hot” causes and define actions to resolve them; these actions can then be rated against both their ease of implementation and the expense of implementation. The team first implementing those actions that are both easy and inexpensive!

The fishbone diagram and the data can be revisited on a regular basis as time passes to see how actions taken affect the problem in question. Thus you can drive continuous process improvement.

Select and Implement your Improvements

Your analysis of your potential causes may direct you to one specific reason for the problem you are experiencing or it may point you at a whole handful or more reasons. The important thing however it to solve all of them so that your problem is removed.

However deciding how to solve your root cause may require you to undertake a whole new brainstorming and fish bone diagramming session; this time looking at different methods to solve the problem that you have highlighted rather than identifying the root cause.

Continuous Process Improvement Tools

Quality Tools Fishbone or Ishikawa Diagram
Quality Tools Fishbone or Ishikawa Diagram | Source

Continuous Process Improvement Using Fishbone or Ishikawa Diagrams

Your analysis of your Fishbone diagram will likely be based in some respects to data that you gather to either confirm or dismiss the potential causes that you have highlighted. You will need to use a host of other quality tools to help you with your data collection and analysis as well as managing the overall process.

On its own the ishikawa diagram is a powerful tool but with the other quality tools used correctly you can quickly highlight and solve the problems facing your business.

You can get more information about the other quality tools by reading the seven tools for quality. These all compliment your use of the Fishbone diagram.

Fishbone Video

Continuous Process Improvement Using Fishbone Video


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    • LeanMan profile imageAUTHOR


      5 years ago from At the Gemba

      You are welcome Shirley, I hope you are not doing her assignment about fishbone for her!

    • profile image

      Shirley C. Perez 

      5 years ago

      Thanks for the great information, it is very helpful to us especillay that my daughter is asking me to make research on her report about causes and effect of fishbone diagram, so helpful.

    • MichaelGallinger profile image


      8 years ago from Detroit, MI

      Nice share, a good read thanks!

    • martinyz profile image


      8 years ago

      I agree. Fishbone diagram is an effective brainstorming tool. Great article.

    • LeanMan profile imageAUTHOR


      9 years ago from At the Gemba

      Thank your for your great comments Knowledge Speaks, the fishbone diagram is a favorite of mine for driving continuous process improvement in any company.

    • KnowledgeSpeaks profile image


      9 years ago from Oakland, CA

      Wow! This was great. I've never heard of the fishbone process, but it looks like a pretty powerful tool for identifying problems and working out the causes in a team/group setting. Then brainstorming solutions. Thanks for the detailed information!


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