Quality
Fishbone / Ishikawa
ishikawa diagram · cause and effect diagram · fishbone diagram
TL;DR
A cause-and-effect diagram that visually organises potential causes of a problem into categories (often 6M: Man, Machine, Method, Material, Measurement, Mother nature).
Developed by Kaoru Ishikawa, the fishbone diagram is a brainstorming and structuring tool used in RCA when a problem has multiple potential contributors. The 6M categories (sometimes 4M, 5M, 8M, or service-industry variants like 4P) keep teams from anchoring on one cause too early.
Fishbone is a candidate-generation tool, not a verification tool — once causes are mapped, the team still needs data to confirm which branches are actually contributing.
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