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5 Whys: Finding the Root Cause

When a problem presents itself, ask "Why?" five times until you reach the root cause.


  • 5 Whys tool instructions, example, and template

The key to solving a problem is to first truly understand it. Often, our focus shifts too quickly from the problem to the solution, and we try to solve a problem before comprehending its root cause. What we think is the cause, however, is sometimes just another symptom.

One way to identify the root cause of a problem is to ask “Why?” five times. When a problem presents itself, ask “Why did this happen?” Then, don’t stop at the answer to this first question. Ask “Why?” again and again until you reach the root cause.

This technique is attributed to Taiichi Ohno, father of the Toyota Production System, which revolutionized automobile manufacturing with methods now known as Lean. It’s important to note that there may be multiple root causes of a problem, and that different people who see different parts of the system may answer the questions differently. For a more comprehensive tool, please see RCA2: Improving Root Cause Analyses and Actions to Prevent Harm.

*NOTE: Before filling out the templates, first save the PDF files to your computer. Then open and use that version of the tool. Otherwise, your changes will not be saved.

Ask "Why?" Five Times

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