Stability

Stability (or deviation) is a total variation in measures obtained with measurement system, measuring a single characteristic in the same part or standard during a long period of time.

When stability related to measurement system subject is considered, it becomes extremely important to differ what is, normally, known as measurement system stability; that is, the quantity of total variation in the system tendency during a period in a part or standard part, and static stability, a more general term that is applied not only to measurement disposal stability, but also to repeatability, tendency, general process, etc.

It's important to recognize that two measurement systems measuring the same standard part exist, both demonstrating static stability, but, even so, one system can have a higher variation, in its tendency during a period, than the other one.

By static point of view, they are equally stable. By a traditional point of view of measure device stability, the system with the highest tendency variation during a period is considered less stable than other one with less variation.

To control and evaluate the measurement system stability, use a control letter, type XBR (averages and amplitudes), once you do not need to calculate Stability index; so this can be also used to measure an improvement, but control letter shows, visually, this improvement.

M.S.A. Graphic by Stability

To generate a M.S.A. per Stability graphic, perform a M.S.A Graphic Query. and select in the parameter Type, option Stability.