Developed by Kaoru Ishikawa (Guide to Quality Control, 1968).
Lays out the possible causes of a defect or failure on branches by category, such as method, machine, material, and people, so no family of causes is skipped.
When to reach for it
When a defect, a broken process, or an incident that keeps returning needs its root cause found and the first plausible explanation should not end the search.
How it runs
- Write the effect at the head of the diagram.
- Draw a main branch for each cause category.
- Brainstorm causes along each branch.
- Ask why each cause occurs, and add the sub-causes.
- Pick the likeliest causes and test them with data.
Where it sits in SOLVE eX
Go to the source
- Guide to Quality Control, JUSE, 1968