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Have I reached a cause I can actually act on?

Follow a chain of causes and test each link with the reverse read: does the cause actually produce the effect above it?

5 Whys Chain · analyze · White Belt · free, no account needed

Use this when

  • A problem keeps coming back after being fixed
  • Your root cause analysis ended at someone’s behaviour
  • You need to trace one specific failure back to its origin

5 Whys Chain

sandbox
    When to stop

    Not at five. Five is a rule of thumb — some chains end at three, some need seven. Stop when the cause is something you can change, and changing it would stop the effect.

    A good chain usually ends at a design decision, not at a person. If yours ends at someone’s behaviour, it stopped one why early.

    Source: Ohno (1988), Toyota Production System — “by repeating why five times, the nature of the problem as well as its solution becomes clear.”

    How this is calculated

    No computation. Enforces the reverse-read check at every link.

    Source: Ohno, T. (1988), Toyota Production System — 'by repeating why five times, the nature of the problem as well as its solution becomes clear.'

    Learn the method