Affinity Diagram

Definition
Systematically asking why an event occurs or a condition exists. The question "why?" is applied to each response until the root cause of the event or condition is found. Sometimes the root cause is identified by the 2nd or 3rd "why." In other situations it may take 6-7 "why's" to get to the root cause. Try to get to the 5th level without getting to an absurd level of detail.