Terminology
The following definitions describe the terms used in
a gage R&R study.
- Gage
- any device used to obtain measurements, for example,
a micrometer or a gasket thickness gage.
- Condition
- typically an operator, but can be
thought of more generically as any condition affecting the
measurements. For example, with an automated process,
condition
might be a set-up procedure or an environmental condition such
as temperature. For the remainder of this appendix,
condition is referred to as operator.
- Trial
- a set of measurements on all parts taken
by one operator. Multiple trials help separate
the gage variability (repeatability) from the variability
contributed by operators (reproducibility).
- Part
- the item that is measured, for example, a gasket.
The parts selected
should represent the entire operating range
(variability) of the process.
- Measurement System
-
the complete process used to obtain
measurements. This includes people, gages, operations, and
procedures.
- Repeatability
-
the variation resulting from repeated
measurements taken on the same part with the same gage
by the same operator. Repeatability is the gage or equipment
variation.
- Reproducibility
-
the variation in the average
of the measurements resulting when different
operators using the same gage take measurements on the same part.
Reproducibility is the operator-to-operator variability.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.