Five Whys and Six Universal Questions


  • To help at the problem definition stage to quickly determine the root cause of a problem.
  • Simple and easy to learn and apply.


Start with looking at any problem and asking “why”? and “what caused this problem”? The first “why” generally prompts a second, third, fourth and fifth “why”…until the root cause becomes apparent.

For example, why has the machine stopped?
A fuse blew because of overload
Why was there an overload?
Not enough lubrication for bearings
Why not enough lubrication?
Pump wasn’t pumping enough
And so on…

Six universal questions: What? Where? When? How? Why? Who?


  • If the “why’s” don’t prompt a fairly quick answer to the “root cause” it means the problem is more complex and may need another technique.