Fishbone Diagram cause and Effect Analysis
Project Manager’s Resource
This tool is also called a cause and effect diagram or an Ishikawa diagram.
These names can be used interchangeably.
The left side of the diagram is where the causes are listed. The causes are broken out into
major cause categories. The causes you identify will be placed in the appropriate cause categories as you
build the diagram.
The diagram looks like the skeleton of a fish, which is where the fishbone name comes from.
A cause and effect diagram can be created in six steps…
The first step of any problem solving activity is to define the problem. You want to make sure that you define
the problem correctly and that everyone agrees on the problem statement.
Once your problem statement is ready, write it in the box on the right hand side of the diagram.
In a manufacturing environment, the traditional categories are…
In a service organization, the traditional categories are…
You can start with those categories or use a different set that is more applicable for your problem. There isn’t
a perfect set or specified number of categories. Use what makes sense for your problem.
Brainstorming the causes of the problem is where most of the effort in creating your Ishikawa diagram takes place.
Ideally, each cause should only be placed in one category. However, some of the “People” causes may belong in
multiple categories. For example, Lack of Training may be a legitimate cause for incorrect usage of
Machinery as well as ignorance about a specific Method.
This step can also be done for the deeper causes that are identified. Generally, you can stop going deeper when
a cause is controlled one level of management removed from your group. Use your judgment to decide when to stop.
The final step for creating a fishbone diagram is to identify the root causes of the problem. This can be done in several ways…
Fishbone diagrams are an excellent way to explore and visually depict the causes of a problem. They
enable the root causes of a problem to be detERMined. This will help you be more effective by focusing your
actions on the true causes of a problem and not on its symptoms.
Learn problem solving techniques and strategies that can help you effectively handle the challenges you face everyday. Improve your problem solving skills using these methods.