The 5 Whys is an iterative question-asking technique used to explore the cause-and-effect relationships underlying a particular problem. The primary goal of the technique is to determine the root cause of a defect or problem. (The “5” in the name derives from an empirical observation on the number of iterations typically required to resolve the problem.)
A Few Illustrative Examples
The Washington Monument was disintegrating…
- Why? Use of harsh cleaning chemicals.
- Why? To clean pigeon poop (can’t have one of our nation’s most powerful symbols covered in crap, can we?)
- Why so many pigeons? They like to eat spiders and there are a lot of spiders at the monument.
- Why so many spiders? They like to eat gnats and there are lots of gnats at the monument.
- Why so many gnats? They are attracted to the lights that are turned on at dusk to illuminate the monument.
Solution: Turn on the lights after dusk via timer / photocell
Sven’s was late for work (again) this morning …
- Why? He couldn’t get his car started and had to take the bus…
- Why? Because he coasted into his driveway last night because he ran out of gas.
- Why? Because he didn’t buy any gas on his way to home.
- Why? Because he didn’t have any money.
- Why? Because he lost it all in a poker game.
- Why? ….
Solution: I’m not sure what the solution is above, but you get the idea… the actual numbers of “why’s” is not important as long as you get to the root cause.
Take the Five Whys for a Spin