is a Cause and Effect Diagram? Description
The Cause and Effect Diagram (Fishbone Diagram) from Japanese quality
control statistician Kaoru Ishikawa is a graphical technique that can be used
in teams to identify and arrange the causes of an event or problem or outcome.
It graphically illustrates the hierarchical relationship between the causes
according to their level of importance or detail and a given outcome. Also
called: Ishikawa Diagram.
Origin of the Fishbone Diagram. History
The Fishbone Diagram was invented by Professor Kaoru Ishikawa of Tokyo
University, a highly regarded Japanese expert in quality management. He first
used it in 1943 to help explain to a group of engineers at Kawasaki Steel
Works how a complex set of factors could be related to help understand a problem.
Usage of the Cause and Effect Diagram | Fishbone Diagram. Applications
- Concentrating on a complex problem in a team effort. Compare:
8D Problem Solving
- Identify all causes and the the root causes for a specific effect, problem,
- Analyze and relate some of the interactions among the factors affecting
a particular process or effect.
- Enable corrective action.
Steps in creating an Ishikawa Diagram. Process
- Explain the purpose of the meeting. Then identify, and clearly state,
and agree on the problem or effect to be analyzed.
Position a whiteboard or flipchart so that everyone can see
it. Draw a box containing the problem or effect on the right side of the
diagram with a horizontal spine.
- Conduct a Brainstorming session.
As a first draft, for the main branches you can use the following Categories:
- Services industry: the 8 Ps: People, Product/Service, Price, Promotion,
Policies, Processes, Procedures, Place/Plant/Technology.
- Manufacturing: the 6 Ms: Manpower, Methods, Measurements, Machinery,
Materials, Mother Nature (environment).
- Use the above categories by asking for example: What are the People
issues affecting/causing the problem?
Identify the main causes contributing to the effect
being studied. This could be done applying a Pareto Analysis (80/20 rule)
or a Root Cause Analysis.
These main causes become the labels for the sub branches of
- For each major sub branch, identify other specific factors which may
be the causes of the effect. Ask: Why is this cause happening?
- Identify increasingly more detailed levels of causes and continue organizing
them under related causes or categories.
- Analyze the diagram.
- Act on the diagram. Remove the causes of the problem. Generic systematic
approaches for this are the Deming Cycle
Strengths the Cause and Effect Diagram. Benefits
- Helps to find and consider all possible causes of the problem,
rather than just the ones that are most obvious.
- Helps to determine the root causes of a problem or quality characteristic
in a structured way.
- Encourages group participation and utilizes group knowledge of
- Helps to focus on the causes of the issue without resorting to
complaints and irrelevant discussion.
- Uses an orderly, easy-to-read format to diagram cause-and-effect
- Increases knowledge of the process by helping everyone to learn
more about the factors at work and how they relate.
- Identifies areas for further study where there is a lack of sufficient
Limitations of the Ishikawa Diagram. Disadvantages
- Not particularly useful for extremely complex problems, where many causes
and many problems are interrelated.
Assumptions of the Fishbone Diagram. Conditions
- A problem is composed of a limited number of causes, which are in turn
also composed of sub causes.
- Distinguishing these causes and sub causes is a useful first step to
deal with the problem.
Book: Kaoru Ishikawa - Guide to Quality Control -
Cause and Effect Diagram (Fishbone Diagram) - Ishikawa Special Interest Group
Special Interest Group (51 members)
Cause and Effect Diagram: Next Steps
It is well known that C&E analysis is a good tool for trouble shooting. My point is there can be many causes while drawing the C&E diagram. Once th...
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Compare with the Cause and Effect Diagram:
8D Problem Solving
| Root Cause Analysis
| Theory of Constraints
| Dialectical Inquiry
| Mind Mapping |
| Delphi Method
Strategic Reasoning |
Action Learning |
Six Thinking Hats
| Kepner-Tregoe Matrix
| RACI |
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