How do the 5 Whys technique and a fishbone diagram complement each other?

• A. 5 Whys helps uncover root causes, while a fishbone organizes causes into categories for thorough analysis.
• B. 5 Whys replaces the need for a fishbone.
• C. They are identical methods.
• D. Fishbone eliminates the need to ask why.

Answer: (A)

The power of these two tools comes from how they complement each other in root-cause analysis. The 5 Whys digs into the cause-and-effect chain by repeatedly asking why, until you reach a fundamental root cause. A fishbone diagram visualizes potential causes and groups them into categories (such as People, Process, Equipment, Materials, Environment, and Methods), helping you see gaps and ensure you consider all areas.

Used together, you’d map out possible causes on the fishbone to guide a thorough exploration, then apply the 5 Whys to the most promising branches to drill down to the true root cause. For example, if late deliveries appear, the fishbone might highlight Process and People as likely areas; you’d then drill down on those branches with Why questions to uncover the underlying reasons, such as a bottleneck in change orders or inadequate planning.

The other options aren’t correct because these tools don’t replace each other, they aren’t identical, and one does not eliminate the need to ask why.