How To Conduct Effective Root Cause Analysis

The ultimate goal of Root Cause Analysis (RCA) is to eliminate the actual cause of the problem. If a corrective action, or a series of actions, is implemented and eliminates the cause – thereby eliminating the possibility of recurrence – then that would satisfy the criteria for effective root cause analysis and corrective action.

There are many types of RCA tools available to organizations, including 5 Why?, Fault Tree Analysis, Interrelation Diagrams, Ishikawa Diagrams (Fishbone, Cause and Effect) and many others. A great example is the 5 Why? method: starting with the incident itself, an RCA team would continue asking “Why did this happen?” until they arrive at the root cause. Refer to the following example:

5 Why? - An Example

Problem: Procedure SOP 1234, Revision 0 was found in use at Work Center #3. Revision 4 is the current version registered in the document control database.

1. Why did this happen? - Revision 0 was photocopied for Work Center #3 when the SOP was launched.

2. Why? - Work Center #3 was not on the distribution list for required documents and updates.

3. Why? - Document controller was not informed of new Work Center launch.

4. Why? - Documnet controller was not included in planning for Work Center launches.

5. Why? - Engineering group failed to realize need for documents related to work center operations.

At first glance, without doing any RCA, the immediate re-action would be to provide the Work Center with the most current version of the document to satisfy the requirement. But, without finding why this happened in the first place, the problem is likely to be repeated when the SOP goes through its next revision. By addressing the nonconformity at the system (or process) level, the corrective action team is forced to investigate further to determine how widespread the problem is and then address the larger contributing factors to the problem.

But how can a corrective action to the problem be verified for effectiveness?

Considering the problem in our example would likely be the result of an internal or external audit observation, it would make sense to use an audit for verification purposes. In some situations it might take a period of months to pass before an audit would be suitable to evaluate the effectiveness of the actions taken. If the problem has not recurred since the implementation of the corrective actions, then we could assume that the root cause has been correctly identified and eliminated. If there are similar problems found on subsequent verification audits, then the RCA process would need to be revisited to initiate new corrective actions based on the results.

The end result of utilizing sound root cause analysis practices should be effective corrective action. The end result of effective corrective action should be improved processes, and ultimately improved customer satisfaction. Regardless of the nonconformity’s source, organizations that only take action on the incidents are bound to repeat the same ineffective corrective actions over and over again. By applying good investigative tools and taking appropriate action of the causes of problems, repeat issues can become a thing of the past.

*This commentary is an excerpt of a longer article, which can be found at

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Charles J. Hellier has been active in the technology of nondestructive testing and related quality and inspection fields since 1957. Here he talks with Quality's managing editor, Michelle Bangert, about the importance of training.
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