Root Cause Analysis Explained

Root Cause Analysis (RCA) is a problem-solving technique targeted at identifying the actual root cause, or the reason for a nonconformity. A root cause is just what it sounds like: the “root” of the problem. The need for RCA stems from the fact that the elimination of the symptoms of the problems is not alone sufficient to address the problem, it must be addressed at the source. If you solve a problem at this root level, it is highly probable that you can prevent its recurrence. 

Basic Steps: Root Cause Analysis

Root Cause Analysis (RCA) uses a specific set of steps, with associated tools, to find the primary cause of the problem, so that you can:

  • Determine what happened (Problem Description)
  • Determine why it happened (Root Cause Analysis)
  • Figure out what to do to reduce the likelihood that it will happen again (Corrective Actions)

It is usually easy to determine what happened, but more difficult to determine why it happened. Only if we do a good job of determining why it happened can we implement appropriate actions to ensure it does not happen again. This leads us to performing a proper and thorough RCA.

A search of the web will reveal a multitude of ways to approach RCA, some more complex than others. The basic approach to RCA can be explained in the five steps below:

  • Define the Problem
  • Collect Data
  • Identify Possible Causal Factors
  • Identify the Root Cause
  • Recommend and Implement Solutions

Defining the problem is usually the easiest step, and the step that led to the whole discussion of RCA. What exactly happened? Usually, it is a failure to comply with a specification, procedure, standard or regulation.

Collecting the data involves gathering the evidence to prove the failure. How long has the problem existed and what is the impact? Were other products or processes impacted? This will often involve gathering people from other departments. RCAs can rarely be effectively completed by only one person. Subject Matter Experts (SME) from various impacted departments are usually necessary.

Identifying the possible causal factors can be challenging. The most common mistake in RCA analysis is just to grab the most obvious causal factor and move on to corrective actions, but you need to drill deeper before moving on to the next step. What sequence of events led to the problem? What conditions allowed the problem to occur and what other problems surround the occurrence of the main problem?  Identifying the causal factors is the most crucial part of the RCA analysis. Without proper identification, the corrective actions may not be appropriate and thus the problem may reoccur. 

There are numerous tools to help drill down to the correct causal factors, one of the easiest is the “5 Whys”.  Start with the problem and ask a ‘why’ question about the problem. The next ‘why’ question you ask should then follow on from the answer to the first question. Here is an example:

  1. Why? – The final product arrived broken at the customer’s facility.
  2. Why? – It was damaged during shipping.
  3. Why? – The shipping instructions from the customer were not followed.
  4. Why? – The instructions were never communicated from the Sales department to the Shipping department.
  5. Why? – There is no process in place to communicate these requirements.

You could possibly take this to a 6th or 7th Why, but 5 is usually enough to get to the root cause of the problem.

Identify the root cause. The example above illustrates how it is important to drill down to the true root cause.  If we just stopped at the first “Why” our corrective action might be just to ship the customer a replacement product, but by getting down to the true root cause we will fix the problem to ensure it never happens again.

Implementing corrective actions is the final step. How will the solution be implemented? Who will be responsible for it, and what are the risks of implementing the solution? Analyze your cause-and-effect process, and identify the changes needed for various systems. It is also important that you plan ahead to predict the effects of your solution. This way, you can spot potential failures before they happen.  

Again, referring to our example above, the corrective action may be to implement a proper communication tool between Sales and Shipping. The tool may be updating your sales procedure requiring that customer requirements be added to your ERP system by the Sales team and the Sales Manager is responsible for the updating the procedure. 


In summary, it is critical to perform RCA correctly to ensure corrective actions are implemented that will prevent reoccurrence of the same problem. A good RCA takes time and usually takes a team of SMEs. Not doing an effective RCA will lead to “band-aid” fixes and not real solutions.