#4 – 2 Reasons to Do a Cause & Effect Diagram

The #4 Classic Lean Leadership post is a tool commonly used in Lean Six Sigma problem solving. That tool is the Cause & Effect (aka Fishbone) Diagram. You’ll notice that the illustration is a hand drawn C&E on a white board. I chose this illustration because I am a big fan of practical problem solving. Here is #4 on the list:

A hand drawn Fishbone Diagram

A hand drawn Cause & Effect Diagram

The Fishbone diagram is also known as the Cause & Effect (C & E) diagram or as the Ishikawa diagram referring to its originator, Professor Kaoru Ishikawa.  The C & E diagram is a good tool when you need to identify the root cause of a problem.  It is also a good tool when there are several possible causes to explore.  Using the Ishikawa diagram enables you to brainstorm and collect possible causes in a group setting.

The mechanics of a Fishbone diagram are not too difficult:

  1. Identify the problem.  Be careful to keep the scope small and manageable.   Using the Pareto Principle is a great way to narrow the scope.
  2. Write a problem statement on a dry-erase board or flip chart.  Draw a box or circle around this statement.
  3. Draw the main bones of the diagram.
  4. Label the bones.  The categories are easier to remember if you call it 4 ME:  Man (People), Machine (Equipment), Method (Procedures), Materials, Environment. See below for more on the 4 ME.
  5. Brainstorm causes and record them on the bones (see diagram).  Capture the causes and avoid solutions at this point.  “Poor Quality Raw Ingredients” is better than “Need a new vendor.”
  6. Identify which causes are most likely to cause the problem and to have the biggest impact.  Validate that there is a true cause and effect with these conditions.
  7. Perform a Root Cause Analysis for the leading causes.  Some people like to do the 5 Why RCA right on the Fishbone diagram.  Pete Abilla shows how you can do this at shmula.com.  This works with a simple 5 Why but you might find it difficult if it turns into a complex multiple path 5 Why.
  8. Identify and implement countermeasures.

More detail about the 4 ME catagories:

  • Man (People) - anyone involved in the process and contributes to the undesired effect.  Names are not needed.  Capture the contributing factors such as not following SOP’s.
  • Machine – equipment, computers, tools, etc.
  • Materials – consumable supplies, packing or raw ingredients, etc.
  • Methods – policies, procedures, common practices
  • Environment – time, temperature, company culture, etc.
  • Some people also use Management, Measurement, and Maintenance.

Two watch outs when doing an Ishikawa diagram:

  • Keep you scope small.  You can get what Jay Arthur calls a whalebone in Lean Six Sigma Demystified if you are not careful.
  • Don’t spend too much time debating where to place a particular cause.  It won’t matter as much as finding the right countermeasure.

You can solve a lot of issues using a few of the right tools.  Pareto charts, Fishbone diagrams, and the 5 Why Root Cause Analysis work very well together to prioritize, identify, and resolve issues.  What can you solve using these tools today?
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About Christian Paulsen

Christian Paulsen is an Executive Consultant with 20 years of Lean Manufacturing. Chris adds value to organizations by driving process improvement and bottom line savings. Chris intends to help others by sharing the lessons learned after a quarter century of operational leadership, marriage, parenting, and even longer as a Cubs fan. Your comments on this blog are welcome. You can also connect with Chris via LinnkedIn, Twitter, and Facebook in the right sidebar. Chris welcomes your comments. Christian's professional services are available by contacting him through LinkedIn (right side bar)
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One Response to #4 – 2 Reasons to Do a Cause & Effect Diagram

  1. Pingback: #4 - 2 Reasons to Do a Cause & Effect Diagram | Visualisation | Scoop.it

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