By Ruth Hill and the Mind Tools Team
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5 Whys

Getting to the Root of a Problem Quickly

Learn how to drill down into a problem,
to get to its root and solve it quickly and effectively.

Have you ever had a problem that refused to go away? No matter what you did, sooner or later it would return, perhaps in another form.

Stubborn and recurrent problems are often symptoms of deeper issues. A "quick fix" may seem convenient, but it's really just a temporary solution and it may solve only part of the problem.

To solve it properly, you need to drill down through the symptoms to the underlying cause. This article looks at Sakichi Toyoda's 5 Whys technique – a simple but powerful tool for quickly uncovering the root of a problem, so that you can deal with it once and for all.

About the Tool

Sakichi Toyoda, one of the fathers of the Japanese industrial revolution, developed the technique in the 1930s. He was an industrialist, inventor and founder of Toyota Industries. His technique became popular in the 1970s and Toyota still uses it to solve problems today.

Toyota has a "go and see" philosophy. This means that its decision making is based upon an in-depth understanding of the processes and conditions on the shop floor, rather than reflecting what someone in a boardroom thinks might be happening.

The 5 Whys technique is true to this tradition, and it is most effective when the answers come from people who have hands-on experience of the process being examined. It is remarkably simple: when a problem occurs, you uncover its nature and source by asking "why" no fewer than five times. Here it is in action:

Problem: Your client is refusing to pay for the leaflets you printed for them.

  1. Why? The delivery was late, so the leaflets couldn't be used.
  2. Why? The job took longer than we anticipated.
  3. Why? We ran out of printer ink.
  4. Why? The ink was all used up on a big, last-minute order.
  5. Why? We didn't have enough in stock, and we couldn't order it in quickly enough.

Counter-measure: We need to find a supplier who can deliver ink at very short notice.

When to Use the Tool

You can use the 5 Whys in troubleshooting, quality improvement and problem solving, but it is best for simple or moderately difficult problems.

For more complex or critical problems, it can lead you to pursue a single track of enquiry when there could be multiple causes. Here, a wider-ranging method such as Cause and Effect Analysis may be more effective.

This simple technique, however, can often quickly direct you to the root of the problem. So, whenever a system or process isn't working properly, give it a try before you embark on a more in-depth approach.

The simplicity of this tool gives it great flexibility, too, and it combines well with other methods and techniques. It is often associated with lean manufacturing (also part of the Toyota Production System), where it is used to identify and eliminate wasteful practices. It is also used in the analysis phase of the Six Sigma quality improvement methodology.

How to Use the Tool

The 5 Whys is a simple, practical tool that is very easy to use. When a problem arises, simply keep asking the question "why" until you reach the underlying source of the problem, and until a robust counter-measure becomes apparent.

Note:

The 5 Whys uses "counter-measures," rather than solutions. A counter-measure is an action or set of actions that seeks to prevent the problem arising again, while a solution just seeks to deal with the situation. As such, counter-measures are more robust, and are more likely to prevent the problem from recurring.

Each time you ask "why," look for an answer that is grounded in fact: it must be an account of things that have actually happened – not events that might have happened. This prevents the 5 Whys becoming just a process of deductive reasoning, which can generate a number of possible causes and, sometimes, create more confusion.

Keep asking "why" until you feel confident that you have identified the root cause and can go no further. At this point, an appropriate counter-measure should become evident. If you're not sure whether you have uncovered the real root cause, consider using a more in-depth problem-solving technique like Root Cause Analysis .

Key Points

The 5 Whys strategy is an easy to use, effective tool for uncovering the root of a problem. You can use it in troubleshooting, problem solving and quality improvement initiatives.

Start with a problem and ask "why" it is occurring. Make sure that your answer is grounded in fact, then ask "why" again. Continue the process until you reach the root cause of the problem, and you can identify a counter-measure that prevents it recurring.

Bear in mind that this questioning process is best suited to simple to moderately-difficult problems. Complex problems may benefit from a more detailed approach (although using 5 Whys will still give you useful insights.)

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Comments (24)
  • Over a month ago Yolande wrote
    Thanks for adding your thoughts, marcj. It's always valuable to learn more about a technique or tool and we appreciate that you took the time to share your knowledge with all of us.

    Yolandé
    Mind Tools Team
  • Over a month ago marcj wrote
    Remember you have only reached a true root cause when the statement is in the form 'what's wrong with what'.

    The technique can be extended to what's known as a 3 legged 5Y to identify systemic root causes and detection causes.

    So first look for the technical root cause, this must be done first. So in the above example we ran out of stock and couldn't replenish fast enough.

    Then look for the systemic root cause, why did our system let us pick this supplier - did it include an interrogation of their response time, why did we think it wasn't important or did we simply not consider it.

    Then look for the detection failure that didn't flag up the stock was running low. This also gives us another systemic issue concerning how we set up minimum stock levels in our system when we either set up a new supplier or change our rate of consumption.

    Hope this helps

    Marc
  • Over a month ago Michele wrote
    Hi serpiro,

    The 5 Whys technique arose out of the Japanese industrial revolution as a tool to improve quality and productivity on production lines. As with all quality improvement tools, data needed to be factual (observable and repeatable) for it to be usable. You're right in saying that the 5 Whys is not appropriate in determining the causes of conflict or people related issues. Human dynamics are situational and complex and do not lend themselves to cause and effect analyses.

    Michele
    Mind Tools Team
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