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Sunday, February 10, 2008

Root Cause Analysis

Root cause analysis (RCA) is a class of problem solving methods aimed at identifying the root causes of problems or events. The practice of RCA is predicated on the belief that problems are best solved by attempting to correct or eliminate root causes, as opposed to merely addressing the immediately obvious symptoms. By directing corrective measures at root causes, it is hoped that the likelihood of problem recurrence will be minimized. However, it is recognized that complete prevention of recurrence by a single intervention is not always possible. Thus, RCA is often considered to be an iterative process, and is frequently viewed as a tool of continuous improvement.

Root cause analysis is not a single, sharply defined methodology; there are many different tools, processes, and philosophies of RCA in existence. However, most of these can be classed into five, very-broadly defined "schools" that are named here by their basic fields of origin: safety-based, production-based, process-based, failure-based, and systems-based.

Despite the seeming disparity in purpose and definition among the various schools of root cause analysis, there are some general principles that could be considered as universal. Similarly, it is possible to define a general process for performing RCA.

General principles of root cause analysis

  1. Aiming corrective measures at root causes is more effective than merely treating the symptoms of a problem.
  2. To be effective, RCA must be performed systematically, and conclusions must be backed up by evidence.
  3. There is usually more than one root cause for any given problem.

General process for performing and documenting an RCA-based Corrective Action

Notice that RCA (in steps 3, 4 and 5) forms the most critical part of successful corrective action, because it directs the corrective action at the root of the problem.

  1. Define the problem.
  2. Gather data/evidence.
  3. Identify issues that contributed to the problem.
  4. Find root causes.
  5. Develop solution recommendations.
  6. Implement the recommendations.
  7. Observe the recommended solutions to ensure effectiveness.

[edit] Root cause analysis techniques

  • 5 Whys
  • Failure mode and effects analysis
  • Pareto analysis
  • Fault tree analysis
  • Bayesian inference
  • Ishikawa diagram, also known as the fishbone diagram or cause and effect diagram
  • Barrier analysis - a technique often used in particularly in process industries. It is based on tracing energy flows, with a focus on barriers to those flows, to identify how and why the barriers did not prevent the energy flows from causing harm.
  • Change analysis - an investigation technique often used for problems or accidents. It is based on comparing a situation that does not exhibit the problem to one that does, in order to identify the changes or differences that might explain why the problem occurred.
  • Causal factor tree analysis - a technique based on displaying causal factors in a tree-structure such that cause-effect dependencies are clearly identified.

Basic Elements of Root Cause

  • Materials
    • Defective Raw Material
    • Wrong type for job
    • Lack of raw material
  • Machine/Equipment
    • Incorrect tool selection
    • Poor maintenance or design
    • Poor equipment or tool placement
    • Defective Equipment or tool
  • Environment
    • Orderly workplace
    • Job design or layout of work
    • Surfaces poorly maintained
    • Physical demands of the task
    • Forces of Nature
  • Management
    • No or poor management involvement
    • Inattention to task
    • Task hazards not guarded properly
    • Other (horseplay, inattention....)
    • Stress demands
  • Methods
    • No or poor procedures
    • Practices are not the same as written procedures
    • Poor communication
  • Management System
    • Training or education lacking
    • Poor employee involvement
    • Poor recognition of hazard
    • Previously identified hazards were not eliminated

Here Some Scheme matrix of RCA Download it HERE