<aside> ⭐ The 5 Whys method is an iterative interrogative technique pioneered at Toyota Motor Corporation in the 1930s to explore the cause-and-effect relationships underlying a specific problem. By working back the cause of one effect to another up to five times, designers can expose root causes and explore effective solutions.

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“Be ahead of the times through endless creativity, inquisitiveness and pursuit of improvement.” — Sakichi Toyoda, Japanese industrialist and inventor who formulated the 5 Whys method

See why 5 Whys is such a valuable tool.

Dig Deep to the Root Cause with 5 Whys

To ask why something happened is a natural, effective way to uncover a problem, be it a high bounce rate on a website, a marketplace failure or anything else you may want to know about users, etc. However, cause-and-effect chains can be long and complex. Whether they occur in the natural or human world, end-result events rarely happen in isolation with only one cause to trigger them.

The effects of one action or condition can be so far-reaching that it’s easy to jump to conclusions when you look at the end result. The greater the number of removes—or steps in a cause-and-effect chain—the more effort and insight it will take to work your way back to what actually started the whole sequence of events that ultimately resulted in the problem at hand. If you overlook any factors involved, you might end up making assumptions—and it’s essential to discard assumptions in user experience (UX) design.

The 5 Whys method was developed to work back to a root cause of a mechanical problem by a total of five removes. Toyota’s famous example illustrates the simple nature but immense power of the technique:

1. Why did the robot stop? The circuit overloaded, making a fuse blow.
2. Why? There was insufficient lubrication on the bearings, so they locked up.
3. Why? The oil pump on the robot wasn’t circulating enough oil.
4. Why? The pump intake was clogged with metal shavings.
5. Why? There was no filter on the pump.

In UX design—and particularly service design—system failures can be far more intricate than this. Users are humans who act in complex contexts, and their behaviors (and reasons for these) can be difficult to decipher, especially with so many channels and parts of their user journeys for you to examine. Most of what we first see when we look at an apparent problem (or, rather, its end result) is just on the surface.

Symptoms can be misleading. On that note—and even more importantly for modern designers—the 5 Whys is an essential tool to dig down to root causes on a bigger scale. As cognitive science and usability engineering expert Don Norman advises in his 21st century design, human-centered design and humanity-centered design approaches, designers who want to effect real change in solving complex global-level problems need to get beneath the symptoms and apparent causes to discover and address what’s really going on. If you don’t solve the right problem—and work with the root cause—the symptoms will just come back.