Fishbone

Map multiple possible causes of a specific failure.

Procedure

• Write the observable effect.
• Group candidate causes under process, tools, inputs, people, measurement, and environment.
• Distinguish observations from conjecture within each branch.
• Test the few causes with strongest evidence and greatest impact.

Questions

• Which category has not been examined?
• What measurement distinguishes these causes?

Evidence to collect

• Effect measure
• Cause categories
• Validation experiment

Limits

• The diagram organizes possibilities; it does not establish causation.

Sources

• ASQ, Root Cause Analysis Tools: Main body

Original concise method summary; no reproduced source passages. No claim to ownership of the underlying method. Linked sources retain their own terms.