The 5 Whys

Discover the root causes of any problem.

The 5 whys analysis is used to find the root causes of an observable problem. By asking the question "Why" several times, users begin to separate the symptoms from the causes of the problem. So repeatedly, ask the question "Why?" at least five times, reiterated "Why" must follow each of the respondent's valuable, candid feedback. Further review then helps to discover the layers of symptoms, relations, and the next pertinent question. The main benefits of using the 5 Whys is not only to identify the root cause of a problem, but also to determine the relationship between different root causes.

Created by

What's it about?

The 5 Whys is a lean assessment and analysis tool for problem solving, concept testing, and quality control based primarily on the scientific approach created by Toyota, and adopted by Kaizen, Six Sigma and lean manufacturing practices globally. It starts by identifying the problem at hand, asks "Why?" to determine the main cause(s), the Q/A session is repeated up to four additional times just to identify and reach the root or source cause(s) in order to find a precise and accurate solution which will prevent the problem from recurring.

Who should use it

Best suited for product/service manufacturers, managers, analysts, and creative thinkers interested in problem solving and exploring the causes and associated risks, dependencies and symptoms of the observable problem or challenge.


Who made it?

Sakichi Toyoda

The 5 Whys was built by Sakichi Toyoda (1867 – 1930,) inventor and industrialist, also known as the father of the Japanese industrial revolution, and is the founder of Toyota Industries. He created the 5 Whys as a simple self-assessment and analysis tool to study process related problems and to ensure that the  same problem does not reoccur.

Recent Toolkits