The "Why-Why Analysis," also known as the "5 Whys," is a problem-solving method designed to identify the root cause of a problem by repeatedly asking the question "Why?" typically around five times. This iterative technique traces cause-and-effect relationships underlying a problem in a logical chain until the fundamental cause is uncovered. It was developed by Sakichi Toyoda and first used in the Toyota Production System as a critical root cause analysis tool. This method is widely applied in quality management, Lean manufacturing, Six Sigma, and continuous improvement processes to prevent problem recurrence by addressing root causes rather than symptoms. Key aspects of the Why-Why Analysis include:
- Asking "Why?" successively to delve deeper into the reason behind a problem.
- Working preferably in teams and verifying facts on the actual site and with real data.
- Avoiding assumptions and focusing on a logical chain of cause and effect.
- Stopping the analysis when the root cause is identified, which may take fewer or more than five whys depending on the situation.
- It helps develop problem-solving skills and supports preventive actions.
- The root cause typically points to failures in processes or systems, not just human error.
An example of this method:
Problem: A material did not reach the site on time.
- Why? Because it was dispatched late.
- Why was it dispatched late? Because the material was not ready.
- Why was it not ready? Because the specification arrived late.
- Why did the specification arrive late? Because it was not sent with the purchase order.
- Why was it not sent? Because the responsible person missed it due to a gap in employee induction.
Root cause: A gap in the induction process.
Countermeasure: Improve training for new employees to prevent recurrence.
This technique is simple yet powerful in identifying root causes, fostering preventive measures, and is effective for straightforward to moderately complex problems.
