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What is Root Cause Analysis (RCA)?

Quality Glossary Definition: Root cause analysis

A root cause is defined as a factor that caused a nonconformance and should be permanently eliminated through process improvement.

Root cause analysis (RCA) is defined as a collective term that describes a wide range of approaches, tools, and techniques used to uncover causes of problems.

The highest-level cause of a problem is called the root cause

Root Cause
Root Cause Analysis Diagram

The root cause is the core issue that sets in motion the entire cause-and-effect reaction that ultimately leads to the problem(s).

Some root cause analysis approaches are geared more toward identifying true root causes than others, some are more general problem-solving techniques, and others simply offer support for the core activity of root cause analysis. By becoming acquainted with the root cause analysis toolbox, you’ll be able to apply the appropriate technique or tool to address a specific problem.

History of Root CAuse analysis

Root cause analysis can be traced to the broader field of total quality management (TQM). TQM has developed in different directions, including a number of problem analysis, problem solving, and root cause analysis.

Root cause analysis is part of a more general problem-solving process and an integral part of continuous improvement. Because of this, root cause analysis is one of the core building blocks in an organization’s continuous improvement efforts. It's important to note that root cause analysis in itself will not produce any results. It must be made part of a larger problem-solving effort for quality improvement.

Approaches to Root Cause Analysis

There are many methodologies, approaches, and techniques for conducting root cause analysis. A 2003 U.S. Department of Energy guideline lists the following five:

  1. Events and causal factor analysis: Widely used for major, single-event problems, such as a refinery explosion, this process uses evidence gathered quickly and methodically to establish a timeline for the activities leading up to the accident. Once the timeline has been established, the causal and contributing factors can be identified.
  2. Change analysis: This approach is applicable to situations where a system’s performance has shifted significantly. It explores changes made in people, equipment, information, and more that may have contributed to the change in performance.
  3. Barrier analysis: This technique focuses on what controls are in place in the process to either prevent or detect a problem, and which might have failed.
  4. Management oversight and risk tree analysis: One aspect of this approach is the use of a tree diagram to look at what occurred and why it might have occurred.
  5. Kepner-Tregoe Problem Solving and Decision Making: This model provides four distinct phases for resolving problems:
    1. Situation analysis
    2. Problem analysis
    3. Solution analysis
    4. Potential problem analysis

Conducting Root Cause Analysis

When carrying out root cause analysis methods and processes, it's important to note:

  • While many root cause analysis tools can be used by a single person, the outcome generally is better when a group of people work together to find the problem causes.
  • Those ultimately responsible for removing the identified root cause(s) should be prominent members of the analysis team that sets out to uncover them.

A typical design of a root cause analysis in an organization might follow these steps:

  1. A decision is made to form a small team to conduct the root cause analysis.
  2. Team members are selected from the business process/area of the organization that experiences the problem. The team might be supplemented by:
    • A line manager with decision authority to implement solutions
    • An internal customer from the process with problems
    • A quality improvement expert in the case where the other team members have little experience with this kind of work
  3. The analysis lasts about two months. During the analysis, equal emphasis is placed on defining and understanding the problem, brainstorming its possible causes, analyzing causes and effects, and devising a solution to the problem.
  4. During the analysis period, the team meets at least weekly, sometimes two or three times a week. The meetings are always kept short, at maximum two hours, and since they are meant to be creative in nature, the agenda is quite loose.
  5. One person in the team is assigned the role of making sure the analysis progresses, or tasks are assigned to various members of the team.
  6. Once the solution has been designed and the decision to implement has been taken, it can take anywhere from a day to several months before the change is complete, depending on what is involved in the implementation process.

Root Cause Analysis Case Studies

There are many benefits to implementing root cause analysis. Read the case studies below to learn about successful RCA efforts, or view more ASQ case studies.

Incredible Journey Incredible Journey (Quality Progress)
In response to employee safety concerns and rising workers’ compensation costs, a team at Boeing’s C-17 site developed a root cause analysis process to prevent injury and save money.             
Wind Power Company Gets to the Root of an Icy Issue Wind Power Company Gets to the Root of an Icy Issue (PDF)
After implementing a new root cause analysis method, it saved Clipper Windpower $1 million in lost revenue while increasing customer satisfaction.             
R. L. Polk & Co.: Making Every Issue the Only Issue case study R. L. Polk & Co.: Making Every Issue the Only Issue (PDF)
Annual customer surveys for R. L. Polk & Co. identified opportunities for improvement in customer contact and issue resolution. By following the same steps for every issue and performing full root cause analysis for 100 percent of issues, Polk increased operational excellence and improved customer satisfaction. The team was named a finalist in the 2008 International Team Excellence Award.             
Statistical Engineering to Stabalize Vaccine Supply Statistical Engineering to Stabilize Vaccine Supply (PDF, member exclusive)
See how statistical techniques ranging from simple graphics to sophisticated time series and variance components models helped identify and address root causes of variability in a vaccine supply.             

Additional Resources

Continue your learning with the articles, books, courses, and other resources on root cause analysis listed below.






Adapted from Root Cause Analysis: Simplified Tools and Techniques, Second Edition and Root Cause Analysis: The Core of Problem Solving and Corrective Action, ASQ Quality Press.

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