Fishbone diagram
Collects the possible causes of a problem under six headings: Manpower, Machine, Material, Method, Measurement and Milieu. The fish head is the problem, the bones are cause groups. The point is to sweep every area rather than look for the cause in one place.
Register nowWhen to use it?
- When it is not clear where the cause lies and you want to sweep without skipping an area.
- In team brainstorming, so everyone contributes from their own domain.
- Collecting candidate causes before going into 5 Whys.
Step by step
- 1Write the problem in one sentence at the top and press Start.
- 2Six category boxes appear. Type a possible cause in the field under a box and press Enter.
- 3Edit the problem statement from the header and the items in place inside their boxes.
- 4A project can hold several analyses; each becomes its own card with its own problem statement.
Keyboard shortcuts (desktop)
Tips
- You do not have to fill every category; a category left empty is information too.
- Write what happened, not the symptom: not "it was late" but "the approval sat for three days".
- Take the strongest few candidates into the 5 Whys tool. Ishikawa gives breadth, 5 Whys gives depth.
Worked example
Example: the scrap rate has gone up
In a furniture workshop the defect rate went from 3% to 9% in two months. Instead of hunting a single cause, every candidate is laid out side by side under six headings.
People
- Two experienced carpenters left
- New hires were never trained
- No handover between shifts
Method
- Cutting dimensions are not written down
- Quality is only checked at the end of the line
Machine
- The saw has not been serviced in six months
- The sander drifts out of calibration
Material
- Supplier changed
- Moisture content of the new boards is not measured
With the bones filled in, two headings are visibly more crowded than the rest: people and material. The team starts there. The fishbone does not find the cause — it tells you where to start looking.
Frequently asked questions
What is a fishbone diagram?
A diagram that sorts the possible causes of a problem into categories and lays them out side by side. It is named after the fish skeleton its shape resembles, and is also called an Ishikawa diagram or a cause-and-effect diagram.
What are the 6Ms?
The six classic categories: People, Method, Machine, Material, Measurement and Environment. The goal is not to fill all six but to force your attention in six different directions instead of the one you were already looking at. In service work these headings can and should be changed.
Can I use a fishbone with 5 Whys?
Yes, and it is the most effective way to use either. Spread the candidates with the fishbone, pick the strongest bone, then drill into it with 5 Whys. One gives you breadth, the other depth.
Does a fishbone diagram find the cause?
Not directly — it produces candidates. When the diagram is done you have a list to test, not a proven cause. The next step is checking those candidates against data, which is where Pareto analysis fits well.
Is it free?
Yes. Klarsti is free and ad-free right now, and you do not need an account to draw a fishbone diagram.