A root cause is a factor which caused a nonconformance and should be permanently eliminated through process improvement. Finding the root cause is done through root cause analysis which is a term describing a collective of approaches, tools, and techniques used to find the true causes of problems. Root cause analysis is done to sort through surface level causes until the main root cause is uncovered.1 But how do you know if you are finding real root causes or getting caught in more surface level causes?
Some ways to know if true root causes are not being found are:
- Multiple nonconformances, CAPAs, or other quality records are opened for the same recurring issue(s).
- There is a trend of ineffective CAPAs.
- Many records have “no real” root cause listed.
By implementing a cross-functional team to analyze the potential causes and using root cause analysis tools to fully analyze all possible causes, the real root cause can be identified. Some common root cause analysis tools are 5 whys, fishbone diagram, and webbing. However, there are common pitfalls of using these tools as well.
When utilizing the 5 whys tool the basis is to answer the question ‘why?’ until you get to the root cause.2 However, this can cause problems if you stop after 5 whys but are not yet at the true root cause. On the other hand, the root cause can occasionally be identified after less than 5 whys and answering more may take you down a rabbit hole unnecessarily.
Using a fishbone diagram is a good way to identify potential root causes across multiple areas. These areas become the “bones” of the fish coming out of the “backbone” which stems from the problem statement. Identifying different categories or areas helps to not get pigeonholed into one area when perhaps multiple functions failed to cause the problem.3 One thing that can often go wrong when using a fishbone diagram is having so many potential causes, they do not get fully analyzed to get to the true root cause. This leads to a surplus of work being done to correct these issues, but the source is not addressed.
Webbing is used in a group to create a web of questions that when answered can lead to the root cause needing to be addressed. Starting with a question such as ‘how might we do XYZ?’ where XYZ is performing the task without issues and building on how that may be completed with follow up questions.4 An example would be ‘how might we increase customer satisfaction?’ and some follow up questions would be ‘how might we ship products without nonconformities?’ and ‘how might we detect nonconformances before products are shipped?’. These questions can lead to thinking beyond the usual scope of finding a root cause. However, this can also lead to chaos if not facilitated properly. The questions need to be constructive and lead to greater thoughts and ideas to solve the problem at hand.
Root cause analysis is the first step in solving the true problem and using the correct tools the correct way can make a difference in finding the true root cause.
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1 ASQ What is root cause analysis (RCA)? Retrieved on 05-14-19 at https://asq.org/quality-resources/root-cause-analysis
2 ISIXSIGMA The 5 whys: a simple tool in value stream analysis retrieved on 05-14-19 at https://www.isixsigma.com/tools-templates/value-stream-mapping/5-whys-simple-tool-value-stream-analysis/
3 ISIXSIGMA THE CAUSE AND EFFECT (A.K.A. FISHBONE) DIAGRAM retrieved on 05-14-19 at https://www.isixsigma.com/tools-templates/cause-effect/cause-and-effect-aka-fishbone-diagram/
4 ISIXSIGMA REVEAL ASSUMPTIONS AND FIND ROOT CAUSES WITH WEBBING retrieved on 05-14-19 at https://www.isixsigma.com/tools-templates/brainstorming/reveal-assumptions-and-find-root-causes-webbing/