I learned a valuable tool '5-Why' on a training workshop led by Stu Lloyd from Hotheads-Innovation. I read a few articles and summarized the main points of 5-Why as below:
“If you don’t ask the right questions, you don’t get the right answers. A question asked in the right way often points to its own answer. Asking questions is the ABC of diagnosis. Only the inquiring mind solves problems.” – Edward Hodnett
5 Why is a problem solving technique pioneered by Toyota Motor Corporation. The 5 Why concept is simple. If problem solvers ask the question “Why?” five times successively, the root cause will present itself by the 4th or 5th Why. Often, the 5th Why points directly at the management systems and practices allowing the problem to exist.
Benefits of the 5 Whys
Help identify the root cause of a problem.
Determine the relationship between different root causes of a problem.
One of the simplest tools; easy to complete without statistical analysis.
When Is 5 Whys Most Useful?
When problems involve human factors or interactions.
In day-to-day business life; can be used within or without a Six Sigma project.
How to Complete the 5 Whys
Write down the specific problem. Writing the issue helps you formalize the problem and describe it completely. It also helps a team focus on the same problem.
Ask Why the problem happens and write the answer down below the problem.
If the answer you just provided doesn’t identify the root cause of the problem that you wrote down in Step 1, ask Why again and write that answer down.
Loop back to step 3 until the team is in agreement that the problem’s root cause is identified. Again, this may take fewer or more times than five Whys.
5 Whys Examples
5 Whys and the Fishbone Diagram
The 5 Whys can be used individually or as a part of the fishbone (also known as the cause and effect or Ishikawa) diagram. The fishbone diagram helps you explore all potential or real causes that result in a single defect or failure. Once all inputs are established on the fishbone, you can use the 5 Whys technique to drill down to the root causes.