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FISHBONE DIAGRAM
Fishbone (Ishikawa) cause-and-effect builder organized around the 6Ms: Methods, Machines, Materials, Measurements, Manpower, and Environment. Add candidate causes by category, see the diagram render live, then run a 5 Why on the most likely ones.
FAQ
QUESTIONS PLANT MANAGERS ASK
WHAT ARE THE 6MS?
Methods, Machines, Materials, Measurements, Manpower, and Mother Nature (environment). They are the standard cause categories for manufacturing fishbone diagrams. The categories force you to look across all six lenses so you do not anchor on the obvious cause.
IS A FISHBONE THE SAME AS 5 WHY?
No. A fishbone surfaces candidate causes by category. A 5 Why drills down through one chain of causation. Use them in sequence: fishbone first to organize the candidates, then 5 Why on the most likely two or three to find the root.
HOW MANY CAUSES SHOULD EACH BRANCH HAVE?
Typically two to five per category. If a category has zero causes, you have probably not gone and looked. If a category has more than seven, the problem is too broad and you should split it into separate fishbones. The point of the diagram is breadth, not depth.
MY TEAM ALWAYS LISTS CAUSES UNDER MANPOWER. IS THAT A PROBLEM?
Yes. Causes that look like “operator error” are almost always system failures: training was inadequate, the procedure was unclear, the visual standard was missing, the supervisor was not present. Push those causes into Methods or Measurements.
WHEN IS A FISHBONE THE WRONG TOOL?
When you already know what is wrong. If you have one strong hypothesis, skip the fishbone and go directly to root cause analysis. The fishbone is for problems with multiple plausible causes that need to be sorted before you investigate.
BUILT BY OPERATORS, NOT CONSULTANTS