The 5 Why’s method is a deductive root-cause analysis technique.
The technique consists of asking “why” at least five times while reaching the root cause of a problem to solve. Indeed, from experience, stopping at two or three degrees of “why” does not necessarily lead to the actual root cause of a problem. To solve problems effectively, you must identify the root causes and ensure your solutions directly address them.
Therefore, here are key points to consider while using the 5 Why’s technique:
- Be grounded in reality: at each level of “why,” go and see facts to verify that it is a “real” cause.
- Trace back the chain of causality in the opposite direction to verify that the cause identified at level N-1 directly and indisputably generates the cause at level N.
- You might need more or fewer levels for the “whys,” depending on the cases.
We want to go deeper enough to uncover the fundamental reason for the problem, enabling effective and sustainable solutions.
Identifying root causes is not exclusively a matter of mental reasoning. It needs to come from reality. Thus, each root cause hypothesis requires a confirmation method. The latter is a fact observation where operations are happening or even local experimentation to confirm the root causes hypothesis.
Identifying root causes is crucial while conducting a problem-solving approach (for example, a PDCA).