Comparison
Five whysvsRoot cause
Five whys
you asked why five times and ended up at a deploy process nobody had questioned in two years.
A technique of repeatedly asking why to get past the immediate trigger to something more fundamental. It is useful for getting a conversation moving and structurally misleading if taken literally, because it produces a single chain of causes when real failures have several. Treat it as a prompt rather than a method, and stop when the answers become organisational fiction rather than when you reach five.
Full entry →Root cause
the report named one cause, and three of the people who were there could each name a different one.
The single underlying reason a failure occurred — a framing borrowed from mechanical systems that fits software poorly. Complex systems fail through combinations, so the search for one cause usually stops at the most recent human action, which is the least useful place to stop. Reviews that ask what conditions made the failure possible produce better actions than ones that ask what the root cause was.
Full entry →