5 whys

http://smartmanagement.info/world-class-manufacturing/5-whys/
Example 5 whys
The patient was late in theatre, it caused a delay. Why?
There was a long wait for a trolley. Why?
A replacement trolley had to be found. Why?
The original trolley's safety rail was worn and had eventually broken. Why?
It had not been regularly checked for wear. Why?
The root cause - there is no equipment maintenance schedule. Setting up a proper maintenance schedule helps ensure that patients should never again be late due to faulty equipment. This reduces delays and improves flow. If you simply repair the trolley or do a one-off safety rail check, the problem may happen again sometime in the future.