Framework
Root Cause

Fishbone Diagram

Causes grouped under 6 Ms

Best for
spreading the search for causes
Time
30–60 min
Difficulty
Beginner
Example

Diagnosing why a manufacturing line's defect rate doubled

Causes by the 6 Ms
  1. Manpower — new operators promoted without full re-training
  2. Method — checklist last revised 18 months ago, doesn't match new line
  3. Machine — calibration sensor drift on station 3
  4. Material — new supplier batch with wider tolerance band
  5. Measurement — QC sampling rate dropped from 1/50 to 1/200
  6. Mother nature — humidity spike during heatwave week

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Root Cause

Current Reality Tree

Logical tree of undesirable effects

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