5 Whys is a brainstorming tool that asks increasingly granular why questions about a problem or process, seeking to understand the root cause or actual problem. The 5 Whys can be used to define a problem or to begin seeking causes.
Example
A team addressing a problem of customer satisfaction found from the feedback forms that show a lower-than-normal satisfaction with food quality over the past week.
The team first asks: Why are customers dissatisfied with the food?
Looking at feedback tied to orders, the team notes that the customers who are rating the food poorly are mostly customers who ordered hamburgers of some type. The answer to the first question is that the customers are dissatisfied with the food because they are dissatisfied with the hamburgers
The team then asks: Why are customers dissatisfied with hamburgers?
The team looks at written feedback on forms or speaks with customers directly and discovers that many customers feel that their hamburgers were undercooked. The new answer is that customers are dissatisfied with hamburgers because the meat is
undercooked.
The 3rd question: Why is the meat undercooked?
An investigation into the kitchen reveals that the grill is not properly calibrated and is providing inconsistent results.
Lastly: Why is the grill not properly calibrated?
Further investigation shows that the morning shift, responsible for calibrating the grill, has a new grill cook. During training, education on performing this function was omitted. The grill is not properly calibrated because the employee responsible was not properly trained.
Now the team has a specific cause and a solution: train the grill cook