Why did the root cause analysis yield unwanted results?
John is driving to the plant earlier than usual today. He is thinking to himself that his days just keep getting longer since being promoted to Production Manager. John isn’t even half-way to the plant when his cell phone starts ringing. Terry, the Third Shift Supervisor is calling to tell John the filler on the priority line is down.
John asks, “What is it this time?”
Terry: “That’s the bad part. We lost a drive belt again and it was the last one. We are going to have to rush one in here just to get the line going again.”
John: “I can’t believe it! We just did a 5-Why on that. I led the team myself and was sure we had a good solution….”
While many people find the 5-Why Root Cause Analysis tool to be very effective in finding the root causes, it’s not going to solve every issue on the first try. There are many reasons why it may not work. It’s important to note that this is part of the learning process, especially if the 5-Why is a new tool to the team. A few of the more common issues that inhibit the success of a 5-Why include:
- Inadequate understanding of the issue: Go to the scene of the crime and see what happened to the extent that it is possible.
- Preconceived answers to the problem: Sometimes they are right. Sometimes they are not. I am particularly wary of 5-Why’s that go directly to an answer discussed prior to the analysis. Encourage your team to consider other possibilities.
- Multiple root causes: There are often multiple root causes. While sporadic issues may have just one, chronic issue almost always have multiple root causes. This is another reason to urge your team to consider all possibilities.
- Ineffective countermeasures: Teams that are able to determine the root cause can usually find good countermeasures. Check to see if the countermeasures are implemented properly.
As John and his team saw with their filler drive belt, doing a 5-Why Analysis is not guarantee that the problem is solved. There will be times when you have to modify the countermeasures. You may even have to go back to the drawing board and do the 5-Why again. Follow-up is critical as discussed in 7 Steps to 5-Why. You should have a PDCA Cycle mindset to ensure success. Do you have examples of 5-Why’s that did not solve the issue on the first try?
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Lean Leadership 
Great post, Christian. While I believe the 5 Why approach can be helpful it also does not promote the use of a confirmation test. A test to verify if you have found the root cause. It may be implied or assumed as good problem solving but because so many people don’t practice good problem solving methodology it needs to be stated explicitly. A confirmation test will tell you for sure if the 5 Why approach helped you find the root cause.
Thank you, Matt. Many problem solving efforts fall short due to inadequate confirmation or follow-up. Your insight is appreciated.
A good way to test the 5 Why got to root cause is with reverse logic. For example, if the root cause was a, you can test by saying THEREFORE b happened, THEREFORE c occurred and so on.
It’s right to say that 5 Why is a skill that needs continual practice and honing.
Stephen-using reverse logic is a good way to test if the theory makes sense before testing it in practice. Thanks for your insight.