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Five Why’s: The Power of Diagnostic Questioning

The “Five Why’s” technique is a useful diagnostic technique originated at the Toyota Motor Corporation. The car manufacturing industry was undergoing a significant evolution and quality became a top priority for automakers. Other companies developed similar techniques for similar reasons, but they referred to them by other names.


The “Five Why’s” is a tool I use frequently when diagnosing the reason a business event or metric went wrong and I need to arrive at a root cause. Once the root cause is known then a remedy can be identified, and preventive measures can be put in place.

The premise behind the technique is to explore the cause and effect relationship of an underlying problem, the goal of which is to identify the root cause by continually asking “why” until the answer is found. Each answer forms the basis for the next “why.” Sometimes one arrives at the answer in less than five iterations. The number 5 was arrived at through experience and understanding that it was the number of iterations needed to arrive at the final answer, the root cause.

There have been many times in my career when this technique was very effective. Although it was designed as a manufacturing technique, I found that I can use it in almost every function. Here is one of my favorite examples which took more than “Five Why’s” to get to the root cause:

Situation: Profits are well below the plan.

Why? Online sales are significantly below expectations.

Why? The conversion rate (percentage of people who come to the website and buy) has dropped over the last few weeks.

Why? Too many people are leaving the site as soon as they arrive and not staying around to shop and buy.

Why? The site visitors are less qualified.

Why? We changed the vendor and type of prospective customer lists we buy for our marketing campaigns so we could generate more site visits for the same cost.

Why? We did not have enough money in the budget to increase site visits with our current vendor.

Why? During the budgeting process we were asked to trim our costs. We reduced our marketing budget and purchased cheaper lists as a result.

Root Cause: Instead of focusing on a proven model, the team tried to cut costs in order to achieve their objectives instead of continuing with a formula that was working. The solution was to avoid major changes to the formula, but instead make minor changes to fine tune it. As it turns out, they had to spend almost twice the amount of marketing dollars to achieve the same revenue goal, and operating income fell dramatically as a result.

There are many other examples where I used this methodology to arrive at the proper root cause.

This methodology can be used to solve business issues in all areas including sales, finance, human resources, operations, manufacturing and even in our personal lives. One should never use this in people-related conversations, especially employee development and coaching.

Not all problems have a single root cause. If one wishes to uncover multiple root causes, the method must be repeated asking a different sequence of questions each time.

The method provides no hard and fast rules about what lines of questions to explore, or how long to continue the search for additional root causes. Thus, even when the method is closely followed, the outcome still depends upon the knowledge and persistence of the people involved.

In conclusion, working through Five Why’s is a valuable process to determine true root cause. Once used a few times, the team members in the chain start to realize that this is part of the culture and will begin using the methodology to troubleshoot problems and arrive at the right answer without the need for an executive review.

I hope this article has been useful. Please drop me a note in the comment section below, or privately through the Contact Me page if you have any questions, comments or ideas that could be helpful to others.

Have a great day!


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© T. Kahler Coaching, LLC

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