Which tool is used in root-cause analysis to repeatedly ask 'why' until root cause is found?

Which tool is used in root-cause analysis to repeatedly ask 'why' until root cause is found?

• A. Ishikawa Diagram
• B. Pareto Analysis
• C. Failure Modes and Effects Analysis
• D. The Five Whys

Answer: (D)

Uncovering root causes through repeated questioning is the main idea here. The Five Whys is the tool designed for that exact process: start with the problem and ask why it happened, then take that answer and ask why again, continuing this chain until you reach a cause that can no longer be explained by a higher-level reason. This approach helps you move beyond surface symptoms to the underlying factors that set the sequence of events in motion. By iterating the why, you chain causation back to root conditions, such as a flaw in a process, policy gap, or missing control, rather than stopping at a noticeable effect. In contrast, an Ishikawa (fishbone) diagram helps organize potential causes into categories and brainstorm possibilities, which is great for structure and coverage but doesn’t enforce the stepwise, cause-and-effect interrogation by itself. Pareto Analysis focuses on prioritizing issues by impact or frequency, using the 80/20 principle, not on drilling down to root causes. Failure Modes and Effects Analysis systematically assesses potential failures and their consequences, often with scoring, but again it isn’t defined by the repeated why questioning to reach a single root cause.

Uncovering root causes through repeated questioning is the main idea here. The Five Whys is the tool designed for that exact process: start with the problem and ask why it happened, then take that answer and ask why again, continuing this chain until you reach a cause that can no longer be explained by a higher-level reason.

This approach helps you move beyond surface symptoms to the underlying factors that set the sequence of events in motion. By iterating the why, you chain causation back to root conditions, such as a flaw in a process, policy gap, or missing control, rather than stopping at a noticeable effect.

In contrast, an Ishikawa (fishbone) diagram helps organize potential causes into categories and brainstorm possibilities, which is great for structure and coverage but doesn’t enforce the stepwise, cause-and-effect interrogation by itself. Pareto Analysis focuses on prioritizing issues by impact or frequency, using the 80/20 principle, not on drilling down to root causes. Failure Modes and Effects Analysis systematically assesses potential failures and their consequences, often with scoring, but again it isn’t defined by the repeated why questioning to reach a single root cause.