Knowledge Base · Seeing Problems
What is a fishbone (Ishikawa) diagram, and when do I use one?
A fishbone diagram is a visual map of every possible cause of one problem, grouped into categories on a diagram shaped like a fish skeleton. The problem sits at the head and the cause categories form the bones. Use it with a team on a complex problem that may have several causes, before you start analysing any of them.
The tool is named after its creator, Dr Kaoru Ishikawa, and is also called an Ishikawa diagram. You start with a horizontal spine that ends at the head, where the problem is stated. From that spine, diagonal bones branch off, one per category of possible cause, and the team hangs smaller bones off each one for the specific causes it suspects.
The book uses six standard categories, often called the 6 Ms:
- Man (People): anyone who plays a part in the process.
- Method (Process): how the work is done: its steps, procedures and policies.
- Machine (Equipment): the equipment, tools and technology the work relies on.
- Materials: the supplies, parts and raw materials going into the work.
- Measurement: the metrics, inspections and data used to judge the work.
- Environment: conditions around the work, such as place, timing, temperature and culture.
Use it when a problem is complex and could have multiple causes, and you need the bigger picture before deciding where to investigate further. The glossary frames the team use the same way: gather a group, get every possible cause for a problem out onto the diagram, and only then begin the analysis. It organises suspicion. It does not, on its own, prove which cause is real.
Build a fishbone diagram in ClarionEX (free in Lite)
Related questions
- Should I use a 5 Whys or a fishbone diagram?
- What is root cause analysis?
- How do I run a 5 Whys analysis?
Source: Continuous Improvement in the Workplace, Ch. 3 (Learning to See) and the CI glossary in the book's Appendix.