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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Really interesting post, I had not ever heard of approaching a task or problem this way!
Thanks for sharing!
Thanks for the feedback. It’s always good to hear from you.
I like using the Fish Bone to get ideas out on paper and have people “empty their pockets.” Then I use that to create experiments to see if the idea is the root cause or not. Before creating the experiments, I ask a series of questions specific to the situation to see if we can eliminate any potential causes based on logic.
Matt-sounds like you have great methodology for the fishbone. Thanks for sharing your insight.
I am going to try this diagram and see how it goes. I have never thought of approaching a problem from this angle. Often diagrams have the “problem” at the top or the start, and the solutions fan out from there. I prefer the fishbone diagram because it “attacks” the problem and gets to the root of the cause. It also goes a step further to making sure the perceived causes of the problem are the actual causes through validation. A very practical approach.
Great! Let me know if you have any questions & I’d be glad to help. Please let us know how it goes.
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I have used fishbone diagram a few times along with Kepner Tregoe method of identifying the potential causes of problem and then ranking them in order to determine what factors should be evaluated prospectively through experimental designs and which ones can be evaluated through pertinent “prior knowledge” or retrospective analyses.
I could see the essence of your experience in the Ishikawa. You are right the tool like this will solve many problem, with out applying complicated softwares.
Yes, no software required! Thanks for your comments.
I like your post. It is exactly how I was taught to do root cause when utilizing the Fishbone diagram. I noticed though a lot of my peers and students were often nervous of performing a Fishbone because of how complicated it can become and how it can lead you down so many roads. I decided to adapt the Fishbone by incorporating the Pareto principle and enhanced it further visually. I call it the Tailed Fishbone.
After the team completes the Fishbone, I have them vote on their top 1-3 causes per category (I.E. man, machine, environment, etc). After I have the top item per category I let them vote one more time on the biggest cause (the one that must be eliminated above all else). I then perform a 5-why analysis on this sole winner. After I have my root cause I place it within a tail of the Fishbone and instruct the team that we must cut off the tail in order to eliminate our headache (our problem at the head). I find more often then not each cause is eliminated just by attacking the tail, any left over we follow-up with if we still feel is an issue.
See my PowerPoint presentation on the subject at the bottom of my LinkedIn profile at:
http://www.linkedin.com/in/tsgtmarkadams (click on the View Full Profile icon then screen to the bottom of the page for the presentation)
Thanks for your comments and kind feedback. Your have a good approach for problem solving. I like the powerpoint you have on your LinkedIn profile on this as well. Thanks again.
I always accompany the fishbone diagram with a detailed process map, cause and effect matrix and Failure Mode and Effect Analysis (FMEA). When applied correctly, alignment of these four tools almost certainly assures that you’re on the path to idendifying the root cause(s) and developing solutions to address them.
That’s excellent insight, Ken. Thank you for sharing.
Thanks for sharing the two watch list, Realize many practitioner often missed out the counter-measure by being carried away with constructing fish-bone.
Beside the 4 ME categories, I also use 7ps related to service marketing (Physical evident, place, promotion, price, product, policy and people)
Just curious, Hope you don’t mind Chris. Wonder anyone has done C&E on SWOT.
Below is quick example, how will it look:
Strength- What makes us strength
Weakness- Are we sure the weakness have impact on us
Opportunity- what, Why, how the opportunity is executable
Treat- What influence the treat
It really sounds crazy. Right ? Maybe this was Lean Six Sigma Demystified all about as mentioned in your post. Keeping the scope small does help the team to focus on the problem.
Good Post, keep writing !
Doing a C&E on a SWOT is a great idea. I have not done that myself but it’s seems like a great opportunity. Most of the SWOT’s I’ve done lately have been as part of an assessment of our Lean-TPM progress. We would then use the results to see if we needed to make any changes to our implementation plan or modify our next steps. Depending on the nature of the SWOT you could do the C&E then even some 5-Why’s on select causes.
Great idea! Thank you for sharing.
Very interesting, enjoyed the read
Dave, my pleasure! Thank you for reading this blog and for your feedback.
The two reasons noted in the title are in the article but it’s not made super clear in how the article is written/formatted.
Scott – Thanks for visiting my blog and for your feedback.
All the best,
Chris, superb insight…..learnt a lot from your post as well as from comments provided by several other experts. Regards. Sanjay
Sanjay – thank you for reading and for your comments. I’m glad you find it helpful.
Fishbone is a very strong tool to identify root cause….one this I just wanted to add is to do a pre an post Pareto to check if the problem is repeating or new set is coming…thanks for the article
Thank you for your comments and insights. Pareto charts are great and should be part of the continuous improvement process.