Why Proper Root Cause Analysis Matters

The post below was written by Gemba Academy Master Black Belt Candidate Noah Waech. Noah was also recently on our podcast. Thank you for sharing your knowledge with us, Noah!

 

Root cause analysis can be one of the simplest and most difficult problem-solving methodologies to use from the lean toolbox. It seems simple…ask “why?” five times. When done properly, using the correct tool for the situation, it can be very rewarding to eliminate the root cause of the issue. If you select the incorrect tool or don’t use it properly, root cause analysis can lead you down the incorrect path, potentially blaming others, or lead you towards a solution that seems impossible to implement. I use this simple flow chart to determine where to begin and help determine the correct path when dealing with an issue.

Every issue we deal with can fall into one of these three categories. The process either

• Does not have a documented process or standard to follow
• Has a documented process or standard, but it was not followed
• The process or standard was not correct

When we think of issues in this sense, it really simplifies our thought process for arriving at a solution. 

Taiichi Ohno, a famous Japanese industrial engineer and father of the Toyota Production System, once said “Without standards, there can be no improvement.” This makes the first step of root cause analysis very simple. If there is no standard, system, or documented process to follow, we cannot make any improvements to the process. Our first step will be to document our process. 

If there is a standard, system, or process, then the root cause analysis can begin. Was the standard, system, or process followed? For issues that are simple or well-known, we can use a 5-whys analysis to determine why the process was not followed. A good way to do this is via a simple cause-and-effect tree. If you are able to identify many branches on the cause-and-effect tree, it may be better to use a fishbone diagram. To complete the 5 Whys analysis, this may include a trip to the gemba or interviewing the employees involved with the problem. If the problem is not well understood or there could be multiple reasons for the issue, a fishbone diagram is the best root cause analysis tool to use. It’s very important to focus on failure in the process or standard at this step, instead of assigning blame to the operator. 

Finally, if the process or standard was followed and we had an issue, it’s important to look to see if the process or standard is not correct. This can happen for any number of reasons. Maybe new software was implemented, but the standard was never updated. Maybe an engineering change notice changed the operation. Maybe the process was correct, but too vague to be followed properly. Maybe a new employee was never trained in the process. All of these examples are opportunities for improvement and potentially further root cause analysis to determine why the process changed without updating the standard. 

Using proper root cause analysis is essential to solving problems in your plant. Without guidelines, it’s very difficult to ensure successful improvement.

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