Another technique used in conjunction with PDCA is the 5 Whys, which is a form of root cause analysis in which the user asks a series of five "why" questions about a failure that has occurred, basing each subsequent question on the answer to the previous. There are normally a series of causes stemming from one root cause, and they can be visualized using fishbone diagrams or tables. The Five Whys can be used as a foundational tool in personal improvement, or as a means to create wealth.