Hi:

IIm new at this, so this might look like a stupid question, but here it goes anyway...is there any other way to prove/measure that a process is in control other than with a control chart?

Hi:

IIm new at this, so this might look like a stupid question, but here it goes anyway...is there any other way to prove/measure that a process is in control other than with a control chart?
Leonadro, welcome to the Cove. There are no stupid questions here, so don't worry.
I don't know of any way other than statistically proving it. If you measure something, then the results are the data to use to calculate and verify degree of control.These statistics are the same for control charts or capability studies. You can purchase many kinds of software to crunch all the numbers and provide control limits, capability indicies, and graph all the data too.
Is this the kind of answer you are looking for?

Hi:

IIm new at this, so this might look like a stupid question, but here it goes anyway...is there any other way to prove/measure that a process is in control other than with a control chart?

Leonardo,
Welcome to Cove. There are no stupid questions. All of us here learn from each other by sharing the knowledge. Iam learning a lot of stuff from this forum everyday.Do not hesitate to post questions.

Process can be controlled by designing controls in the system. Example: Closed loop control system (Automation) which measures the output at a desired frequency and feeds back to the system thus controlling the output within desired level.

We can set up to perform this function using statistical control chart principles or just control within desired specification limits. Both are controls.
The former one is statistically controlled.

However, using statistical principles, we will know the difference between random variation and special causes. This way we do not tweak the process too often. Also using control chart principles, we can make sure if the process is stable. Once the process is stable, we can start working on reducing the variation.

Govind.

Welcome to the Cove Leonardo -

The use of the words "prove - in control" rather limits the discussion to control charts but there are other ways to control a process. This can be done with in-process inspection, periododic testing/sampleing or other methods. One you might look at for maintaining control with minimal operator input is "Pre-Control". I have also used "Action Charts" mentioned above by Govind. Depending on what you want to control and the degree of control you wish to maintain, there can be a variety of alternatives to the common "control chart".

Dave

Hi:

IIm new at this, so this might look like a stupid question, but here it goes anyway...is there any other way to prove/measure that a process is in control other than with a control chart?

This is a good question. I'm looking at this from adifferent point of view, in that the control chart does not control process. The C chart is only one of the tools used to monitor the process to indicate whether or not the item is within aceptable limits.
Controlling the process comes in the form of training, proper equipment, maintenance, work flow, etc,etc.

By Leonardo

Im new at this, so this might look like a stupid question, but here it goes anyway...is there any other way to prove/measure that a process is in control other than with a control chart?


Like ralphsulser said:

I don't know of any way other than statistically proving it

I tink that many will not agree but: IMO If the mean and the standard deviation of a sample is the same, the process is the same or "in control" (so "F" and "t" test with for example 90% because is not a controled experiment). I know that the traditional way is without any out of control rules, but not all rules apply to any condition and sometimes a rule of out of control happens and is just by chance (nothing happend).

Welcome to the Cove.

:biglaugh:

Thanks a lot for your replies. You've been very helpful. :)