The 4W's of Problem Scoping are Who, What, Where and Why. These Ws helps in identifying and understanding the problem in a better and efficient manner.
Who - "Who" part helps us in comprehending and categorizing who all are affected directly and indirectly with the problem and who are called the Stake Holders
What - "What" part helps us in understanding and identifying the nature of the problem and how do we get to know what helps to get us know the evidence.
Where - "Where" does the problem arises, situation and the location.