Quality & Quantity (2006) 40:499–518 © Springer 2006
Evaluating the Gauge Repeatability
and Reproducibility for Different Industries
Department of Statistics, National Cheng-Kung University, 1 University Road, Tainan,
Taiwan, R.O.C. 70101
Abstract. Measurement plays a signiﬁcant role in Six sigma program. Usually, the gauge
repeatability and reproducibility (GR&R) study needs to be conducted prior to the process
capability analysis for verifying the accuracy of measuring equipments and helping organi-
zations improve their product and service quality. Therefore, how to ensure the quality of
measurement becomes an important task for quality practitioners. In performing the GR&R
study, most industries are using the acceptance criteria of Precision to Tolerance(P/T) ratio
as stipulated by QS9000. However, the adequacy of applying the same acceptance criteria
to different manufacturing processes is very questionable. In this paper, a statistical method
using the relationship between GR&R and process capability indices is proposed for evaluat-
ing the adequacy of the acceptance criteria of P/T ratio. Finally, a comparative analysis has
also been performed for evaluating the accuracy of GR&R among three methods (ANOVA,
Classical GR&R, and Long Form). Hopefully, the results of this research can provide a
useful reference for quality practitioners in various industries.
Key words: Six sigma program, gauge repeatability and reproducibility, precision to tolerance
(P/T) ratio, ANOVA, classical GR&R method, long form method
Gauge variability plays a key role on quality improvement for the industry.
Only a gauge with acceptable repeatability and reproducibility, the adequacy
of a product’s measurement process can be determined. Recently, gauge var-
iability study has been highly regarded by the quality practitioners when
QS9000 and Six sigma program become fashionable requirements/manage-
ment tools for manufacturing industries. Many companies are now pursuing
the excellence of product and service quality through Six sigma program,
The implementation steps of a Six sigma project D-M-A-I-C are listed as
1. Deﬁne: Deﬁne the processes and their performance standards.
2. Measure: Select CTQ (Critical To Quality) characteristics and verify
the accuracy of measuring equipments.