Perhaps the failure to use these tools properly stems from the misconstrued use of Deming’s PDSA which was change do PDCA. Both Deming and Ishikawa intended their tools to be useful in studying the variation present in a given process. They assumed that users would understand that a process is not singular in its function and that it can include many Tasks with each task having the possibility of contain many Actions (or Inactions). This is why the Ishikawa diagram indicates several possible causes for any one effect. The idea is not to define a single root cause, because that is most likely not possible related to a complex process of tasks and actions. The idea is to address all of the possible causes and Study which ones are the most probable contributors to the effect.

One may never be able to recreate the events which combined together to become the ultimate cause of the event, however with this tool one can discover the most probable common causes of variation, and even determine some special causes of variation and determine if adequate controls are in place to detect the occurrence of the common or special causes of variation identified as a result of the exercise.

Whatever one decides concerning this tool, its best to avoid the trap of “Root Cause” when using it for solving process issues/problems.