Fishbone Diagram (Ishikawa)

A Fishbone diagram is a way to map possible contributors to a defined problem before selecting causes to investigate. It is a hypothesis map, not proof of root cause.

Start with the effect

Write a specific, observable problem at the head of the diagram. “Conveyor stopped during the night shift” is a useful starting point; “poor maintenance” is already an interpretation. Record when and where the stop occurred and what evidence is available.

Organise possible causes

EasyFixProblem starts with People, Process, Equipment, Material, Environment and Measurement categories. Add a cause to the category that helps the team discuss it; rename or add categories when the investigation needs them. The category is a sorting aid, not a verdict.

For a hypothetical conveyor stoppage, a team might list an overload trip under Equipment, a missed inspection under Process and a handover gap under People. Each remains a possible cause until checked against logs, observations or other evidence.

Move from diagram to investigation

  • Ask what evidence would support or rule out each plausible branch.
  • Send relevant causes into Why-Why rather than marking every diagram entry as a root cause.
  • Record multiple branches if the problem has more than one contributor.
  • Keep unsupported branches visible as hypotheses while the team verifies findings.

What the finished work shows

The diagram shows categories and entered causes; the linked Why-Why analysis captures the questions and their verdicts. Actions and effectiveness checks belong later in the same case, so a meeting diagram can be traced back to the underlying investigation.

Continue the investigation

Put it into practice

Start with one case and work from the problem through Fishbone, Why-Why and actions. The Free plan includes one case for one user; exports and AI require a paid plan.

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