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John J. Casey

Quality Insider

Leveraging Five Whys

Get the most for your effort.

Published: Tuesday, August 26, 2008 - 22:00

When I was a boy, my grandmother used to read me nursery rhymes to entertain me and teach me about the world. One has resonated with me for years:

"For want of a nail the shoe was lost
For want of a nail the horse was lost
For want of a horse the warrior was lost
For want of a warrior the battle was lost
For want of a battle the kingdom was lost
All for the want of a nail.

This little poem displays the heart of the five-why problem-solving method that’s used mainly in the automobile industry, especially the Japanese auto industry. Basically, five-why analysis is a fundamental approach to thinking, based on the logical linkage of elements into a cause-and-effect analysis. Look at a problem and ask yourself, “Why did this happen?” Then with each specific answer, repeat the question about five times and you will typically end up with a rather solid root cause. In the poem above, the problem was that the kingdom was lost. The series of why questions leads you through the loss of the battle due to not enough soldiers, and ultimately due to not enough nails in the hands of the blacksmiths.

It’s a simple process of logical connections. It’s a method for problem-solving that gets to some hard-to-identify causes and gives you the opportunity to see the issues that have a leveraging effect on the overall process. The beauty of this simple process is that it gives you great leverage when properly deployed because it takes you to the root of the problem.

Sophisticated problem-solving
Across industry today, you will hear about many advanced problem-solving methods. Popular methods such as Six Sigma approaches, red X approaches, Kepner-Tregoe processes, and others have a definite place in the our world. Some problems are extremely complicated and involve a number of interrelationships.

Sometimes these tools are essential. We all know that if you organize the information about the situation and combine it with properly collected and analyzed data, precise solutions can be found. Most problems don’t require this extreme level of structure and analysis. In fact, many people are intimidated by the statistics and data collection so they stop the problem-solving analysis before they even try, and the organization suffers by having the problem and its effects linger longer than necessary.

A key success factor of any company is to get everyone in the organization involved in the continuous improvement effort. To improve you need to overcome the constraints of today and make your world a better place. In reality, the pursuit of continuous improvement means that your people are engaged in problem-solving.

In The Toyota Way (McGraw-Hill, 2003), Jeffrey Liker explains that the pinnacle of operational effectiveness comes from Toyota’s emphasis on problem-solving. Toyota sees this as the main driver of competitiveness—get everyone in the company involved and working on solving problems. What’s Toyota’s main approach? Five-whys. It’s simple. It’s logical. It’s effective. It looks deep for true root causes. Everyone can do it.

The “therefore” test
The therefore test has proven to be a very reliable method to check the logic of the five-why analysis. When using the five-why method, it’s tricky to keep everyone’s logic straight. Humans have an enormous capacity to think, and we often clutter our thoughts with extraneous information. While five-why is easy to explain, it’s hard to do at first because we will often bring in biased thinking or related information that isn’t on the critical path of the root cause. We often get off on tangents and need a method to keep our thoughts in order.

To do the therefore test, you read the key findings of the analysis in reverse and insert the word therefore between each step. If the stream of logic makes sense in reverse, then the logic is probably solid. In the poem “The Kingdom and the Nail,” the therefore test would look like this:
The blacksmith did not have enough nails, therefore
The horseshoe was not attached, therefore
The warrior could not get to the battle, therefore
The army was outnumbered, therefore
The battle—and ultimately the kingdom—was lost.

This simple test can verify the logic of the five-why and help people see where they’re off on a tangent and give them an easy means to stay on track.

The leverage point
The worst kind of problem you can have is one that your customer discovers. Most plants have problems and they work to minimize the effect of the problem. If they find the issue and keep it away from their customer, they encounter inefficiencies and that’s all. If they have the problem and it gets to their customers, not only do they have the inefficiency, but they also have risked their reputation and violated the trust of their customers. This potentially can affect the company for years, because the customer—in good faith—exchanged their money for your product, and the product failed. They can rationalize that the company has violated their trust. A broken trust can remain for years, and rational thinking can sometimes disappear.

In the five-why approach, a customer problem has at least three root causes that must be found:

The specific cause: Why was the bad product created?
The detection cause: Why did the bad product get through our inspection process?
The systemic cause: Why were our production and inspection processes so weak as to allow the customer to be at risk?

The specific cause
When most people think of problem-solving, they think of the specific root cause. You have a discrepant part, some machine or process wasn’t performed correctly and you think you have found the issue. For example, if there’s a rattling noise in your car and you tighten the loose screw, you haven’t necessarily found the problem because the rattle went away.

Great problem-solving will dig past the symptom (the loose screw) and look at the operation responsible to install and tighten the screw to get to the root cause. It could be a worn tool bit, a defective motor, or operator fatigue. Any one of these are potential root causes that need to be confirmed to find the true root cause.

The detection cause
Every company deploys means to check their work before it goes to their customers. If problems can happen (and they almost always can), the companies that do the best job at protecting the customer from their problems win in the short and long run. The short term is lower customer satisfaction costs, such as repair, replacements, and rework.

The long-term benefit is enhanced reputation and increased customer loyalty. Although shutting off the cause of the problem is great, there’s double gold to be had by analyzing the inspection and detection system to determine how the problem products escaped. When you protect the customer, you have preserved their trust. When they trust you, they are more willing to pay a premium for your product thereby increasing your profits.

Typically there are three aspects that repeatedly surface as holes in the detection system:

Inspection scope: The inspection process has a gap and is not looking for the specific defect. In your planning, you did not think the defect would occur or you took a risk that it wouldn’t happen.
Inspection reliability: The method you have for detection is limited in some way to consistently find and filter the defect. This could be limited by a state-of-the-art process in cost-effective detection, which is especially true in subjective or appearance-type problems.
Detection bypass: Defects normally found by inspection processes get to customers because the products didn’t go through the normal inspection process. In industrial settings, operators will sometimes place suspicious parts in a box—which looks like finished products—and someone else will take the box over to finished part inventory, skipping the detection process completely. This lack of discipline bypassed the inspection process.
Differences in customer expectations standards: When customers' expectations and your standards are misaligned, problems often happen. If you make flip-open cell phones and get constant complaints from mothers with small children, the problem could be that the children are playing with the phone, inducing “Nonadult-like” stress on the phone.

While there are other causes for inspection and detection problems to occur, these three areas account for more than 80 percent of the holes in the detection system.

The systemic cause—the greatest leverage point
Extending the five-why process to the systemic arena is where the huge leverage occurs. In the systemic leg, the problem-solver is looking at the overall management and development system that created the production and detection systems. The problem-solver asks, “Why was the process that we handed to the production people not adequately robust?”

We must look at the management system and the development system, including product, process, and inspection designs, and understand how the engineers and managers let the production people have weak processes in the first place. It can be an approach, a disciplined execution, or business practices and standards that allow the production processes to be insufficient.

By examining systemic issues and finding a root cause—and fixing it—you create massive leverage for your company. These systemic issues touch each and every product you make, current and future. An improvement at the system level spreads across all products and all programs. This is maximum leverage. This is the heart of Toyota’s process and this is where true competitive advantages are born.

When you look at a problem and have the resolve to look past the superficial causes and go deep to the systemic ones, you win and win big. Be the king in the kingdom. Would you like to lose your kingdom for the want of a nail? I doubt it. Have the strength to nail problems down completely.


About The Author

John J. Casey’s picture

John J. Casey

John J. Casey is the senior director of supplier performance at Honeywell Aerospace and is a past chairman of the American Society for Quality (ASQ) Automotive Division. Casey is the author of Strategic Error Proofing: Achieving Success Every Time with Smarter FMEAs (Productivity Press, 2008).