You may remember seeing or having a Jack in the Box toy when you were a child. It looked much like a box and would have a crank on its side that you could turn. It would play a little song, and suddenly the top would fly open and the head of a clown (or something else) would spring out from the top, giving you quite the surprise. There is a phenomenon in processes that takes its name from this childhood toy and the jolt it can give.

Jack in the Box

When you are working with a process, there are certain things that you expect. Sometimes, though, there is an occurrence so out-of-the-ordinary, that it may disrupt the stability of your process. A Jack in the Box can call into question a process’s reliability and strength.

Overview: What is a Jack in the Box?

Jack in the Box can be defined as a variable that appears randomly in response to factors that are not readily apparent.

3 drawbacks and 1 benefit of a Jack in the Box

There are some clear disadvantages to a Jack in the Box, but there is also a benefit to them.


1. Effect on process capability

One drawback of a Jack in the Box is that it can have enough significance to have an effect on process capability.

2. Reliability

A Jack in the Box can cause considerable apprehension as to how reliable a process is.

3. Sourcing the issue can be difficult

Finding the source of the Jack in the Box can be difficult and time-consuming.

A benefit of a Jack in the Box

One benefit of a Jack in the Box is that its occurrence forces us to look at our processes and test them to make sure they are as strong as they can be. It gives us a reason to check when we might not have otherwise.

Why is a Jack in the Box important to understand?

A Jack in the Box is important to understand for the following reasons:

Things happen – It is important to understand that things happen, and a Jack in the Box is not the end of the world. It does not even necessarily mean that there is anything inherently wrong with your process, it just requires some investigation.

Prevent future occurrences – A Jack in the Box can feel random, so in some ways, it is hard to prevent the specific onset factors that led to it. Once it happens, though, you can take precautions to prevent the recurrence of that particular scenario in the future. Understanding what caused the Jack in the Box is integral for preventing them.

TimeĀ – Having an understanding of a Jack in the Box prepares you for when it occurs and that there could be a significant amount of time that needs to be dedicated to finding out where the problem occurred.

An industry example of a Jack in the Box

An analyst is looking at the output of a manufacturing plant and sees that on one day, there is a major change in output that cannot be accounted for. The analyst tells the plant manager about the Jack in the Box and an investigation is launched. It turns out, that was a day there was an attempted strike at the plant that slowed down output significantly for the day but did not come to further fruition.

3 best practices when thinking about a Jack in the Box

Here are some practices to keep in mind when it comes to a Jack in the Box:

1. Check for errors

The Jack in the Box you encounter could be due to an error, whether with measurement or with data entry. Should this be the case, the true process is not represented, and adjustments should be made accordingly.

2. Be sure to deal with them immediately, if values turn out to be accurate

If it turns out that the Jack in the Box is a legitimate value, be sure to find out the cause immediately, in order to prevent future such occurrences and to maintain stability with your process.

3. Do not be concerned that this random occurrence is reflective of future defect rates

Frequently Asked Questions (FAQ) about a Jack in the Box

Can a Jack in the Box be prepared for?

In general, the more thoroughly tested your processes are and the more potential occurrences you have prepared for, the less likelihood there is of encountering a Jack in the Box.

Will a Jack in the Box always affect process capability?

No, while a Jack in the Box has the potential to significantly affect process capability, that does not mean that one always will when it pops up.

Does a Jack in the Box always indicate process instability?

No, there may not be anything inherently wrong with a process, and a Jack in the Box may completely be an anomaly.

Preparing for a Jack in the Box

Thorough testing of processes can be a safeguard against a Jack in the Box. While we cannot prepare for everything, doing all that we can to ensure the strength of processes can help protect against errors. Even with all the preparation, there are simply some things that cannot be planned for. While a Jack in the Box occurrence can feel random, once it happens, there are steps that can be taken to prevent the same Jack in the Box from happening again.

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