The 5 Why process is a method of Root Cause Analysis that consists of asking enough questions to discover the root cause or defect in a system.
It is based on the scientific method and in that way resembles the Attend, Plan, Act, Learn, Improve Cycle. Asking “Why” a problem exists at least five times often drives the investigator towards the real answer. The “real answer” is important so that appropriate countermeasures can be adopted to resolve the issue.
Far too often, anticipated countermeasures do not alter reality in the way we intend because they are targeted at symptoms, rather than the true Root Cause.
Applying a “rote” 5-why analysis is susceptible to criticism in that people tend to stop at symptoms of the problem rather than delve deeper to the root cause. Moreover, investigators are limited by their current knowledge and often will not find causes that they do not already know about or can not imagine exist. Finally, the tendency to “isolate a single root cause” may not be appropriate where each question “could elicit many different root causes.” Like all lean tools, “5-Whys” is a means to an end, not the end in itself. It exists merely to challenge investigators to look deeper. It is up to the investigator to ensure they look deeply enough, through a Systems Thinking lens.