Cause and Effect Diagram – 7 QC Tools

Cause and Effect Diagram is also known as Ishikawa diagrams,  fishbone diagrams, herringbone diagrams and Fishikawa Diagram. Cause & Effect Diagram which was introduced by Kaoru Ishikawa helps to identify many possible causes for an effect or problem. It is used to structure a brainstorming session. It helps in sorting out ideas into useful categories in a short time. The Ideas are usually categorized into four groups namely Men, Machine. Materials and Method. The groups are widely understood as 4M.

Cause and Effect Diagram is followed after a Brain storming session in which the ideas are generated. The Ideas are structured using a Cause & Effect Diagram.


Brainstorming is a means of generating ideas. Brainstorming can be used to identify alternative ways to solve problems. The common principle of brainstorming is to set aside the Judgmental thinking so that many open ended ideas can be generated. They may be validated scientifically to prove or disprove that it is a root cause.


Once the Root cause is arrived the next step is development of the solution. For each root cause grouped under 4M in the fishbone diagrams, the solution must be arrived. Why-Why analysis is usually used to find out the exact root cause for the problem. It starts with asking 5 why’s to any cause that is available in the fishbone diagrams. Once the root cause is solved, naturally the problem is also solved.

why-why analysis

The 7 QC tools help in solving problems very effectively. fishbone diagrams helps in structuring the ideas generated in a brainstorming session done for solving the problem. The fishbone diagrams is followed by Validation and Why-Why analysis to find out the root cause of the problem.

Few books recommended to read on 7QC Tools are given below

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