Method

What is RCA?

Root Cause Analysis

In 30 seconds

Root cause analysis (RCA) is the umbrella term for methods that look for the underlying cause of a problem rather than its visible symptom. The right root cause is a precondition for a corrective action that actually works.

How does it work?

  • The problem is defined clearly: what, where, when, how much.
  • Possible causes are drawn out with tools such as 5 Why, Ishikawa or fault trees.
  • Candidate causes are verified or eliminated with data and tests; action is built on the verified cause.

Often confused with

Possible cause and verified cause

Causes found by brainstorming are candidates. A root cause is only a root cause once it is verified with data or by switching the defect on and off.

Common mistakes

  • Stopping at the first plausible explanation.
  • Blaming a person instead of questioning the system.
  • Acting before candidates are verified.

From a QWorks perspective

In QWorks each root-cause candidate is eliminated with an OK/NOK decision; the decision and its evidence stay with the case.

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