If you are interested in the root of this methodology, consider reading Toyota Production System by Taiichi Ohno. Page 17 starts the discussion on how asking Wh

If you are interested in the root of this methodology, consider reading Toyota Production System by Taiichi Ohno. Page 17 starts the discussion on how asking Why Five times is a method of determining root cause. This book isn't popular, but is worth your time. http://www.amazon.com/Toyota-Production-System-Beyond-Large-Scale/dp/0915299143 http://www.amazon.com/Toyota-Production-System-Beyond-Large-...