ABSTRACT
The 5 Why method is used to dig deeper until the true root cause of an occurrence is identified. The root cause can be pursued by asking why continuously, or the process can be split when an occurrence could have multiple causes (Ohno, 1988). The whys can be, but do not need to be, placed in boxes like a flowchart/ fault tree. The 5 Why method should lead from the proximate cause to the ultimate cause.
