A team wants the deeper cause; which RCA tool should they use?

• A. The Five Whys
• B. Root Cause Diagram
• C. Pareto Analysis
• D. Failure Mode and Effects Analysis

Answer: (A)

The main idea here is drilling down to the true cause by asking why multiple times. The Five Whys helps you peel back layers of symptoms until you reach a fundamental problem, giving you a clear target to fix so the issue doesn’t recur. It’s especially effective when the problem follows a relatively direct chain of events and you want a quick, focused root cause. For example, if a machine stops, you’d ask why it stopped, why that happened, and so on, until you arrive at a core issue such as a maintenance gap or a process deficiency that allowed the failure to occur. Other tools can be useful in different contexts—a fishbone diagram helps map many possible causes, Pareto analysis shows which causes are most significant, and FMEA proactively assesses potential failures and their effects—but they don’t automatically drill down to the single deepest root cause the way the Five Whys does.