Which technique is central to Lean for identifying underlying causes of problems?

• A. Root-cause analysis
• B. Plan-Do-Check-Act
• C. Benchmark
• D. Continuous improvement

Answer: (A)

Root-cause analysis is the technique Lean uses to pinpoint the underlying reason for a problem rather than just treating symptoms. In Lean, the goal is to fix the process so the problem doesn’t recur, which means tracing an issue back to its origin using structured questioning or diagramming. Tools like the 5 Whys or an Ishikawa (fishbone) diagram help teams peel away layers of symptoms until they reach a root cause, such as a missing standard work, a bottleneck, or an unreliable maintenance schedule. Once the true source is identified, the corrective actions can be targeted and effective, preventing similar problems in the future.

Plan-Do-Check-Act is a broad improvement cycle used to test and implement changes, but it is not the specific method for uncovering underlying causes. Benchmarking involves comparing performance to others, not diagnosing what creates the problem. Continuous improvement describes the overall mindset of ongoing enhancement, not the particular technique for identifying root causes.