Using the “Five Whys” to Identify Root Causes

Tajichi Ohno was born in 1912 in Dalian, China. As a young man, he was hired by Toyota Automatic Loom Works. Toyota was later sold to Platt Brothers, a British Company, prompting the Toyoda family to use the sale’s proceeds to begin an automotive manufacturing factory. Ohno stayed with the family and began working as a production engineer towards the end of World War Two.

Japan’s weak productivity and poor automotive quality, compared to the United States, was well known, leading Toyota to begin concentrating on improvement. Ohno, an industrious engineer, put his attention to eliminating inefficiencies in the production line. His personal goal was to match, if not exceed, the productivity of U.S. automotive production. From post-war to the 1970s, Ohno and his co-workers worked systematically at driving out waste and inefficiencies. Their process became known as the Toyota Production System (TPS). And as consumers can attest, the quality of Japanese vehicles soared in the late 20th Century. The irony is that years later American and European automotive manufacturers would copy the TPS.

Ohno’s journey wasn’t easy; he met a lot of resistance from management on the need to radically change production methods. But he persisted. Eventually Toyota, as a huge corporation, embedded quality and the elimination of waste (see lean manufacturing).

One of the thinking processes that Ohno developed has become known as “The Five Whys.” He didn’t see problems in a negative light but rather as an “opportunity in disguise.” The word “Kaizen,” meaning continuous improvement, has become embedded in manufacturing around the world. As Toyota’s website explains on “The Five Whys:”

Observe the production floor without preconceptions. Ask ‘why’ five times about every matter.

[Ohno] used the example of a welding robot stopping in the middle of its operation to demonstrate the usefulness of his method, finally arriving at the root cause of the problem through persistent enquiry:
“Why did the robot stop?”
The circuit has overloaded, causing a fuse to blow.

“Why is the circuit overloaded?”
There was insufficient lubrication on the bearings, so they locked up.

“Why was there insufficient lubrication on the bearings?”
The oil pump on the robot is not circulating sufficient oil.

“Why is the pump not circulating sufficient oil?”
The pump intake is clogged with metal shavings.

“Why is the intake clogged with metal shavings?”
Because there is no filter on the pump.

Through this line of inquiry, it’s possible to identify the root cause of a problem. And it doesn’t have to be a manufacturing process to employ it.

Ohno’s work has been applied not only to manufacturing settings but more broadly to the functioning organizations. Peter Senge, MIT lecturer and author of the acclaimed bestseller The Fifth Discipline: The Art and Practice of the Learning Organization, integrated The Five Whys into System Thinking. Briefly, System Thinking involves stepping back to see the big picture when approaching a problem, and how it is part of a bigger system. So rather than react to a specific event, for example, effort’s needed to identify its relationship to other events. As Senge explains:
“It is a framework for seeing interrelationships rather than things, for seeing patterns of change rather than static ‘snapshots’.”

This is where The Five Whys can be very useful, whether on a production line, an organization’s recruitment process, or an airline’s customer service practices. It enables one to drill down to root causes when problems emerge that initially get blamed on the “system.” What gets overlooked is that human beings created the “system.”

Here’s a simple example of The Five Whys, using the airline industry as an example:

Q. Why did the passenger’s checked bags not arrive at her destination?
Because they were sent to Dallas airport instead of Miami.

Q. Why were her bags sent to Dallas?
Because the baggage handlers weren’t paying attention.

Q. Why were the baggage handlers not paying attention?
Because they’re angry at management with the delay in settling their collective agreement.

Q. Why is there a delay in the agreement?
Because of management’s insistence on a pay freeze because the airline is losing money.

Q. Why is the company losing money?
A. Because it hasn’t invested in a new computerized tracking system as its competitors have done.

This is along the line of enquiry one could take with a problem that plagues airline passengers.

The Five Whys can be a powerful tool in distilling what may first appear as an overly complicated problem with tentacles extending everywhere. However, bringing people together to collaboratively explore a problem can produce, in a relatively short time, surprising solutions.

Effective questioning brings insight, which fuels curiosity, which cultivates wisdom.
— Chip Bell

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