five-whys

Start with a specific, measurable problem statement, then ask "why" iteratively, documenting each answer with supporting evidence. Continue until you reach a systemic process failure, typically around five levels, then design solutions targeting that root cause rather than symptoms.

The Five Whys technique uncovers root causes of recurring problems, system failures, customer churn, delays, and budget overruns. It was developed by Sakichi Toyoda for Toyota and is commonly used in post-mortems and process improvement work.

Five is a guideline, not a rule. Continue asking why until you reach a systemic cause you can act on, which may take fewer or more than five iterations. Stopping early usually leaves you fixing symptoms instead of the root cause.

Analysis fails when answers rely on assumptions instead of data, when the process stops at surface symptoms, or when it devolves into blaming individuals. Verify each answer with evidence and focus on process failures, not people.

Yes, Five Whys works alongside Fishbone diagrams for visualizing cause categories, Pareto analysis for prioritizing problems, Six Sigma DMAIC, and Kaizen improvement cycles. It is also a standard component of incident post-mortem sessions.