Concept of Root Cause Analysis – An Overview
This article may be of further interest for industry fellows struggling with repeated problems in their processes and may be repeated customer complaints and dealing with conducting Root Cause Analysis to determine the immediate Corrective action and preventative actions.
Root Cause Analysis defined by Wilson et al (1993) as an analytic tool that can be used to perform a comprehensive, system-based review of critical incidents. It includes the identification of root and contributory factors, determination of risk reduction strategies, and development of action plans along with measurement strategies to evaluate the effectiveness of plans.
Definition of Root Cause
For Practical purposes, root causes are….
- Specific underlying causes
- Causes which we can reasonably identify
- Causes that we have the ability to resolve
- Causes where we can think of effective solutions to prevent recurrence
- “ Root – Cause analysis is a thinking process that makes use of data a variety of sources to identify the basic reason (s) for the appearance of a problem.”
Root Cause Analysis Assumptions
- “Beneath every problem is a cause for that problem.”
- “If the root cause of a problem is not identified, then one is merely addressing the symptoms and the problem will continue to exist.”
RCA Goals
Identify…, What happened, How it occurred, & Why “it” took place. What we can do to prevent re occurrence
Levels of Causes
- Causal factors: This is not the root cause but a factor that has contributed to the issue occurig and must be addressed in addition to root cause.
Physical Causes: Specific physical item that, if corrected / replaced would fix problem. Tangible, material items failed in some way. E.g. equipment, component, process, raw materials etc.
- Human Causes: A person/persons did not perform an action needed or performed an action leading to something going wrong.
- Organisational cause: Deficiencies in a system, process or policy that people use to make decision or do their work.
Root Cause Analysis
Define the problem
Try and use SMART principles, i.e. Specific; Measurable, Actions oriented; Realistic; Time constrained.
Understand the problem
Check the information, obtaining real data regarding the problem, gaining a clear understanding of the issues. This is when the various tools and techniques, such as Cause and Effect, brainstorming, etc, can be used.
Immediate actions
Implement temporary countermeasures at the place of the problem. ‘The further away from the problem source the solution is determined, the less likely that the solution will be effective’.
Corrective actions
Determine and prioritise the most probable underlying causes of the problem, as the temporary counter-measure may not resolve the root cause. Taking corrective actions to at least mitigate or preferably eliminate the causes.
Confirm the solution
After the measures have been determined and implemented the success of the adopted approach needs to be established. Having confirmed the success of the suggested solution then rules or control methods need to be established that will avoid the problem ever happening again. This is probably the most important phase in the RCA, but the one most often missed.
RCA Tools
Let us Focus on 5 WHY Analysis in the article:
5 Why’s Preparation:
Five why’s is a Root Cause Analysis Tool. Not a problem solving technique. The outcome of a 5 Why’s analysis is one or several root causes that ultimately identify the reason why a problem was originated. There are other similar tools as the ones mentioned below that can be used simultaneously with the 5 Why’s to enhance the thought process and analysis.
Even though the discipline is called 5 Why’s is not always necessary to reach 5 before the root cause of a problem is fully explained; or it may take more than 5 why’s to get to the bottom of it. It will depend on the complexity of the process or the problem itself.
In any case, 5 has been determined, as a rule of thumb, as the number at which most root causes are clearly identified. Do not worry about not meeting or exceeding this number though. Just follow your thought process and let it decide how many Why’s you require to get to the point where the root cause is evident.
It is said that a well-defined problem is a half resolved problem; hence it is important to state the problem as clearly as possible. Whenever possible define the problem in terms of the requirements that are not being met. This will add a reference to the condition that should be and is not.
Any 5 Why’s must address two different problems at the same time. The first part is related to the process that made the defective part.(“Why made?”)
The second one must address the detection system that was not able to detect the defective part before it became a problem. The lack of detection of a defective product is a problem of its own and must be treated independently than the product problem itself. (“Why not detected?”)
The 1st WHY
Clear statement of the reason for the defect or failure to occur, understood even by people that is not familiar with the operation where the problem took place.
Often this 1st Why must be a short, concise sentence that plainly explains the reason. Do not try to justify it, there will be time to do that later on in the following why’s if it is pertinent to the thought process. It is Okay to write it down even if it seems too obvious for you. (It may not seem that obvious to other persons that will read the document).
2nd WHY
A more concise explanation to support the first statement.
Get into the technical arena, the explanation can branch out to several different root causes here. It is OK to follow each of them continuing with their own set of remaining 3 why’s and so forth.
3rd WHY
Do not jump to conclusions yet, follow the regular thought process even though some underlying root causes may start surfacing already.
This 3rd why is critical for a successful transition between the obvious and the not so obvious. The first two why’s have prepared you to focus on the area where the problem could have been originated; the last three why’s will take you to a deeper comprehension of the problem. Visualize the process where the product went through (process mapping) and narrow down the most likely sources for the problem to occur.
You do not need to answer all the why’s at the same time, it is an investigation activity and it will sometimes require you to go to the process and see things you could have missed at first.
You may be missing the obvious by rushing into “logical” explanations”.
4th WHY
Clear your mind from preconceived explanations and start the fourth why with a candid approach. You may have two or more different avenues to explore now, explore them all. Even if one or several of them turn out not to be the root cause of the problem, they may lead to continuous improvements.
This is a good time to include a Cause and Effect analysis and look at the 5 M’s.- Method, Materials, Manning, Machines and Mother Nature
5th WHY
When you finally get to the fifth why, it is likely that you have found a systemic cause. Most of the problems in the process can be traced to them. Even a malfunctioning machine can sometimes be caused by an incorrectly followed Preventive Maintenance or Incorrect machine parameters setup.
When you address a systemic cause, do it across the entire process and detect areas that may be under the same situation even if there are no reported issues yet.
If you have reached the fifth why and you are still dealing with process related cause(s), you may still need one or two more why’s to deep dive into the systemic cause.
Common Mistakes
Unmanageable conclusion, Duplication of the immediate corrective action, proposed action doesn’t prevent re-occurrence, additional controls etc are some of the common mistakes observed in the root cause analysis
Conclusion
A good way to identify if the 5 Why’s was done properly is to try to organize the collected data in one sentence and define it in an understandable manner. If this cannot be done or the sentence is fragmented or meaningless chances are that there is gap between one or several of the why’s. You then must revisit the 5 Why and identify those gaps to fill them in. If there is coherence in the way that the sentence is assembled, it shows consistency on the thought process.
Something like:
“Problem Description” occurred due to “Fifth Why”. This was caused by “Fourth why” mainly because “Third Why” was allowed by “Second why”, and this led to “First Why”.
Challenge the root cause(s) that resulted from the 5 Why’s exercise to try to reproduce the defect. If you cannot there is a very big chance that you have not gotten to the bottom of it yet. If you do reproduce them, move on to the Corrective Action part and congratulate your team for a job well done.