Cause and Effect Diagram – Seven Basic Quality Tools

The first thing you should know about Cause and Effect Diagram is the list of its alternative names. The list includes,

• Fishbone Diagram (because it looks like one)
• Ishikawa Diagram (because the person named Ishikawa developed it)
• Herringbone Diagram

We have covered this in a previous article on PMP Brain Dump

Specifically with regards to quality, this diagram tries to figure out what caused a defect or a problem or an error. To come up with a fishbone diagram,

• List out all the categories of defects that you have identified
• List out all the possible causes of the defects for each category

When you do so, you will be able to see all the possible causes of the defects in one place. By fixing the causes, it will help you prevent the defects in the future.

For example, a failure in a system testing could be due to

• Inexperienced developer
• Improper coding
• Test script errors
• Incorrect environment

Here’s a sample fishbone diagram,

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