The 5 Whys is a technique to get at the root cause of a problem. Sakichi Toyoda developed and used it within Toyota. It’s really simple. Just ask “Why?” five times.

Here’s an example from wikipedia. Problem: The vehicle will not start.

  • Why? – The battery is dead.
  • Why? – The alternator is not functioning.
  • Why? – The alternator belt has broken.
  • Why? – The alternator belt was well beyond its useful service life and not replaced.
  • Why? – The vehicle was not maintained according to the recommended service schedule.

(Of course, your depth doesn’t actually have to be five.) Because good research pushes the depth of “why?”, I’ve been using this strategy to generate deeper research questions. I force myself to keep asking “why?” until I don’t know the answer. Then I look in the literature for it, and if I find an answer, I continue the loop until I get to a question that hasn’t been answered.

This hierarchy of “why”s is actually better displayed as a tree because you can entertain multiple possible answers for the “why” at each level. It’s fun to actually draw it out! If you want to get fancy, you can even add weights on the edges that correspond to how much you believe that child is the answer to its parent question.

(I know this description is calling for an example and photo.. I’ll post one eventually)