Understand
Fishbone diagram
Also called Ishikawa diagram, Cause and effect diagram
Sort the possible causes of a problem into categories along the bones of a fish, so the team looks wider than the first cause it thinks of.
- Time30 to 45 minutes
- People3 to 10 people
- Steps4
What it's for
Put the problem at the head and give each bone a category. The categories make people look for causes in places they would skip, such as tools, policy or the environment, instead of stopping at the obvious one.
It pairs well with five whys: the fishbone finds the candidates, and five whys digs into the ones that matter.
How to run it
Write the problem3 min
State the effect at the head of the fish.
Brainstorm causes15 min
Add possible causes to each category, one per note.
Vote on likely causes5 min3 votes each
Each person votes for the causes they think contribute most.
Dig into the top ones10 min
Ask why for the most-voted causes, or plan how to check them.
Tips
- Rename the categories to fit your problem. The six here are a starting point.
- A cause in several categories is a strong lead. Note where they repeat.
Where it comes from
Kaoru Ishikawa, a Japanese quality-control engineer, developed and popularised the diagram from the 1940s to the 1960s. It became one of the basic tools of quality management.
Pairs well with
Five whys
Ask why a problem happened, then why that happened, until you reach a cause you can fix rather than a symptom.
Affinity mapping
Group a pile of notes into themes by moving similar ones together, then name each theme to see what the pile is telling you.
Premortem
Imagine the project has failed, then work out why, so risks get named while there is still time to act on them.