What are the 5 Whys?

When problems pop up in the workplace, it can be tempting to fix it quickly. However, not finding and addressing the root cause of the issue can lead to recurring mistakes and future problems. An easy way to complete a root cause analysis and uncover deeper issues is with the Five Whys.

Sakichi Toyoda is credited with developing the Five Whys, an important method in the Toyota Production System and Lean manufacturing. It is a simple problem-solving technique in which root cause is identified by asking “Why?” at least five times. The Five Whys are most successful when it is practiced by a team. After a problem happens, a team of frontline operators and workers directly affected are gathered to tackle the issue. The team observes the problem in action and defines it in a concise statement. This is where the first “Why?” will be asked.

From there, “Why?” is asked four more times in succession, and as many times until a list of causes has been compiled. It is important the team be thorough, but not completely exhaustive. The goal is to find the root cause and not be inundated with unreasonable suggestions and problems. If there is more than a singular root cause, your Five Whys analysis may branch off into several different reasons.

Understanding the relationship between the main problem and related causes will help the team develop countermeasures. Team members have the responsibility to carry out countermeasures, implementing corrective actions to protect the process from recurring issues.  The Five Whys emphasizes countermeasures over solutions, as solutions may temporarily eliminate symptoms while countermeasures prevent the problem form happening again. After a set period of time, the team meets again to evaluate efforts and determine if whether or not they had a positive impact.

Although this method is mostly used in problem-solving, the Five Whys can also be particularly useful for troubleshooting or quality improvement, and can be used in Six Sigma as a tool to identify and eliminate waste in the facility.


View all Lean Manufacturing Q&A

Free E-Book

Lean Manufacturing

Minimize waste and maximize efficiency with our step-by-step guide.


Free Samples

Get samples of our most popular products so you can see the quality before you buy.

Other FREE Resources:

Helpful Resources