The Fishbone Diagram

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  • What is a Fishbone Diagram?

–A Fishbone diagram is a “cause and effect” diagram. The importance of the FBD is that is that it uses visual power to highlight the problems and relationship between problems and their potential sources

  • When to use a Fishbone Diagram?

–When a simple approach is needed to reduce the effect of a problem (s)

–When identifying possible causes for a problem

–When problem solving has gone stale and the team needs a fresh approach

This is a typical example of a FBD template. Generally there are 6 major branches (some header titles may be vary):

  • Materials
  • Manpower (People)
  • Machine
  • Method (Process)
  • Measurement
  • Environment

 

Fishbone procedure

1.Agree on a problem statement (effect) and write it at the end of the horizontal arrow.

2. Brainstorm the causes that influence the effect – do this for all categories (branches).

3. Arrange and strategize the causes. Decide on principle causes and show these as the major branches off the horizontal arrow.

4. Create sub-branches for the causes. Continue to sub-divide all the causes for each branch until all causes are included.

5. Review chart to ensure all known causes of variation are included.

Fishbone diagram completed

Once the Fishbone is created, the team should decide:

  • Do we need to collect data at certain processes?
  • Do we need to revisit any causes or factors for reconsideration?
  • Make an action item list for all opportunities and follow through

Good to Great

When a process is predictable (in control), the Fishbone diagram will assist in identifying continuous improvement  opportunities for a better process.

Improvement

When a process is not predictable (out of control), the Fishbone can identify areas for continuous improvement by removing non value added activities to create a more stable process.

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