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Wednesday, March 13, 2013

Root Cause Analysis (RCA) - Basic Quality Concepts

A root cause is a factor that caused a nonconformance and should be permanently eliminated through process improvement.
Root cause analysis is 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
The root cause is “the evil at the bottom” that sets in motion the entire cause-and-effect chain causing 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, while 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.

Excerpted from Root Cause Analysis: Simplified Tools and Techniques, pages 5 and 13.
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When carrying out root cause analysis methods and processes, keep these hints in mind:
  • Many root cause analysis tools can be used by a single person. Nevertheless, 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:
  • A small team is formed to conduct the root cause analysis.
  • 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
  • The analysis lasts about two months, relatively evenly distributed between defining and understanding the problem, brainstorming its possible causes, analyzing causes and effects, and devising a solution to the problem.
  • During this 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.
  • 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.
  • 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.  
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There are many methodologies, approaches, and techniques for conducting root cause analysis. A U.S. Department of Energy (DOE [2003]) guideline lists the following five:
  • 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.
  • 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.
  • 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.
  • 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.
  • Kepner-Tregoe Problem Solving and Decision Making — This model provides four distinct phases for resolving problems:
    • Situation analysis
    • Problem analysis
    • Solution analysis
    • Potential problem analysis
    There are overlaps among these five approaches. For a model incorporating aspects of each, see Root Cause Analysis: The Core of Problem Solving and Corrective Action.
    The book focuses on helping problem solvers differentiate among the generic steps involved in (1) identifying a problem, (2) performing a diagnosis, (3) selecting and implementing solutions, and (4) leveraging and sustaining results.

 

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