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 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:
- Identify the problem. Be careful to keep the scope small and manageable. Using the Pareto Principle is a great way to narrow the scope.
- Write a problem statement on a dry-erase board or flip chart. Draw a box or circle around this statement.
- Draw the main bones of the diagram.
- 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.
- 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.”
- 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.
- 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.
- 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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