Test your knowledge

Interactive: Test your knowledge

1. Is the ‘5 Whys’ method restricted to just 5 questions?

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The 5 Whys method is not restricted to just 5. However, if after asking 5 whys, the issue is fully understood, then the 5 questions could be sufficient.

Stopping at 5 can be a reason that the 5 Whys system may not always be successful.Other reasons could be:
  • Tendency for investigators to stop at symptoms rather than going on to lower-level root causes.
  • Inability to go beyond the investigator's current knowledge, therefore they cannot find causes that they do not already know.
  • Lack of support to help the investigator ask the right ‘why’ questions.
  • The use of the 5 Whys as a stand-alone tool, without using the preparation and preliminary phases required.
  • Investigation stopped at the 5th ‘why’, even though more questions could/should be asked.
  • Results may not always be repeatable - different people using the 5 Whys may come up with different causes for the same problem.
  • Tendency to isolate a single root cause, whereas each question could elicit many different root causes.
  • The output from the use of the 5 Whys tool can lack forms of verification to prove its correctness.