CAUSE AND EFFECT DIAGRAM

Write-up – 4

Understanding Statistical Tools and Techniques

CAUSE AND EFFECT DIAGRAM

Kaoru Ishikawa developed this analysis tool in 1943. This diagram is also known as ‘Ishikawa diagram’ or ‘Fishbone diagram’.

The cause and effect diagram organizes and displays the relationship between different causes for the effect that is being examined. It is a useful tool for opening up thinking in problem solving. It identifies many possible causes for an effect or a problem. This tool can be used to structure a brainstorming session. In fact, the cause and effect diagram helps in organizing the brainstorming process in a systematic way. This is a tool that sorts ideas into different categories.



This tool should be used when you wish to identify possible causes for a problem. Following procedure will be useful:

- Identify the problem on which you wish to draw cause and effect diagram
- Write the problem at the centre right of the writing-board. Draw a box around it and draw a left-side horizontal line running to it.
- Brainstorm the main categories of causes, factors or concerns related to the problem. If you feel difficulty in grouping major categories, then it is better to use generic headings, such as Methods, Machine (equipment), People (human resource), Material, Measurement and Environment. These are commonly identified causes of problems.
- Write the categories of the causes, factors or concerns of the problem as the branches from the main row
- Brainstorm all the possible causes, factors or concerns of the problem. Ask – “Why?”
- Write the generated idea as a branch from the appropriate category. Possible causes, factors or concerns can be written in several places, if they relate to several categories. Example – No internal audit organized in the organization as the trained internal auditor resigned two months back. It can be written along People as well as along measurement.
- Again ask – “Why?” question about each cause. Continue asking – “Why? Why? Why?” and in this way you can generate deeper levels of causes, factors or concerns related to the problem.
- When you are unable to find more ideas, then focus your attention to the diagram where ideas are less.

Brainstorming can be effectively used to generate causes and sub-causes. When completed cause and effect diagram looks like a tree-like structure that indicates many factors including causes and concerns of a problem.

In this way you can now evaluate different causes, factors and concerns to solve a problem.

CAUSE AND EFFECT DIAGRAM WITH ADDITION OF CARDS

The process is similar as mentioned above, however, in the diagram at the cause side two different coloured cards are used to indicate facts in one colour card and ideas on other colour card. Generally facts are written on the left side of the cause spines, whereas ideas for solving the problem or effect are written on the right side of the cause spines. Ideas are then evaluated and selected to solve the problem or concern.

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