Five Why Explained Definition of Five Why

Five Why Explained

Definition of Five Why

The popular tool called 5 why is a problem solving method used to explore the cause and effect relationships of a particular problem.

Sakichi Toyoda, one of the founders of the Toyota Motor Corporation, is credited as the first person to practice 5 Whys analysis and Taiichi Ohno, one of the chief architects of the Toyota Production System, once said that 5 whys analysis was the basis of Toyota's scientific approach... he went on to say that by repeating why five times, the nature of the problem as well as its solution become clear.

It seems that what Mr. Ohno was saying was to not make your method of analysis over complicated... instead just pursue the root cause persistently.

How to Do it

The first step of 5 why analysis is to simply write the problem or problem statement down. After this we ask why the problem exists.At this stage it's important to keep the answers short and to the point.

The third step is to continue asking why on the same point of cause until the root cause or causes are identified.

This is very important as we must be sure to stay focused on the same problem instead of asking 5 different whys on 5 different problems.Another important point I'd like to make is that even though the name of this tool is called 5 why it doesn't mean that we have to end up with exactly 5 whys. Sometimes we'll have more and sometimes we'll have less.

5 Why Examples

While 5 why is not a difficult concept... it does take some practice... so to help move things along we'd like to walk through an example.

Let's assume we're faced with the following problem - the milk is spoiled.

? We then ask the question "why is the milk spoiled" to which the answer is we didn't drink all the milk cartons before expiration.

? We then ask why this was... to which we hear "we had too many cartons in the fridge." ? We then ask why this was to which we hear,"We bought more cartons than we needed at the

store." ? Getting closer to the root cause the team asked why more cartons were bought than what

was needed... to which we learn that there was a sale on milk and we tried to save money.

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So, as we see in this example only 4 whys were needed to get to what the team felt was the root cause of the problem.

Multiple Paths, Multiple Root Causes

In some situations we may face a problem with multiple root causes... when this is the case our 5 whys analysis will take on a slightly different form. So let's see an example of multiple paths and multiple root causes.

In this situation the problem is that the production units per hour is below our target.

? Why is this? Because we're not able to make enough parts per hour. ? Why is this? Because we're losing production opportunities. ? Why are we losing production opportunities? Because of lost and lost parts due to scrap. So,

as we see here there are two reasons identified... thus creating multiple paths. ? When we asked why we are losing time we learned that we're facing cycle time losses and the

fact that the process is not running... so, once again we've created multiple paths. ? Next, in order to better understand why we're experiencing cycle time losses we learn that

loading machine time is taking too long. ? And in an attempt to understand why the process is not running we learn that we have to

clean up. ? Switching back to the loading machine problem we learn that the operator is having to walk 5

feet for material. ? And the reason we're having to clean up is because things are getting dirty. ? Why? Because there are leaks.

So, as we've just seen, 5 why analysis can, and often does, branch out into several paths. Also, as we've already learned, we don't always need to ask why 5 times, especially on additional paths.

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Root Cause Analysis "So what?" Test

Once you and your team are done with your initial 5 whys analysis you're going to want to check the cause and effect logic of your results by asking a simple, one word, question ? so?

? For example, using the last path we could state that there are leaks so it gets dirty... ? So, we clean up... ? So the process is not running... ? So we have lost time... ? So we are losing production opportunities... ? So, we are not able to make enough parts per hour.

So, you see, by simply stating so and working backwards we're able to check to see if our 5 whys analysis makes sense and is logical.

Typical Errors Made

To wrap this less up we'd like to discuss a few of the most typical errors made when doing 5 why analysis.

? The first error occurs when people ask 5 different why questions rather than drilling down on the same point of cause.

? Next, another common error occurs when organizations stop at 5 whys when additional whys, including multiple paths, may be required.

? Third, there is a chance for error when we don't check for a logical cause and effect relationship by asking so what?

? Finally, the last common error of 5 why analysis occurs when we don't go and see in order to verify our assessment is indeed accurate.

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