Terminology

The GAGE Application

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.