Cause-and-effect Diagram and Six M’s

Once the charter is complete and signed by all parties, the team transitions to the Measure phase, where the search starts for potential Xs that influence output. One of the tools is the fishbone diagram. The classic cause-and-effect fishbone has the defect at the end (the stinky head of the fish), and the bones are split up in six categories:

  1. Man (people)
  2. Machines
  3. Material
  4. Methods
  5. Measurements
  6. Mother Nature

Figure 1: Fishbone with Six M’s

Figure 1: Fishbone with Six M's

With each “bone,” the team tries to find various potential Xs that influence the project Y by asking:

  • “How does man (people) negatively influence the defect?”
  • “How do the machines negatively influence the defect?”
  • “How does the material negatively influence the defect?”
  • “How do the methods negatively influence the defect?”
  • “How do the measurements negatively influence the defect?”
  • “How does Mother Nature negatively influence the defect?”

After completing this exercise, the team should have various inputs that can be classified as the six bones. The project team may have more inputs on the material bone, or have more on the people one, but in the end the team will have an idea of where the critical X could be. The next step then is to sort and prioritize the various Xs and start measuring them in conjunction with the Y.



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