Introduction
Measurement systems are essential to the quality of a manufacturing
process. The gages or instruments that take measurements are subject
to variation. Too much variation in the measurement system may mask
variation in the process.
One type of measurement variation is caused by conditions inherent in
gages. This variation, known as repeatability, is obtained when one
person measures the same characteristic several times with the same
gage. Another type of measurement variation, known as reproducibility,
occurs when different individuals measure the same characteristic with
the same gage.
Other sources of measurement variation include part-to-part
variation, accuracy, stability, and linearity.
Two graphical methods for evaluating the measurement system
are range charts and average charts.
Range charts assess repeatability by showing
whether the gage variability is consistent.
Average charts show consistency of operator variability
(reproducibility) and
part-to-part variation.
Two statistical approaches to determining gage R&R are the average and range
method and the variance components method. The
variance components method can provide more information, is more
accurate, and is more flexible than the average and range
method.
The GAGE application makes it easy for you
to enter your data, create range and average charts, and determine
gage R&R.
Whether you use the average and range method or the more
powerful variance components method, the GAGE application reports
the results in a standard form. It allows you to save the graphs
for later reference, and it allows you to save the
reports. You can save the data in a SAS data set
for subsequent gage analysis or for more extensive
analysis using other components of the SAS System.
Because gage R&R techniques are open to local interpretation, this
application has been designed so that it can be modified to
suit the needs of your company.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
