Multivariate Capability Indices for Processes with Asymmetric Tolerances

Abstract

The capability indices for only one characteristic of quality with symmetrical tolerances have been widely studied. This paper deals with the situation of several characteristics supervised simultaneously, for a rectangular tolerance region and an unspecified target inside this region. New capability indices are suggested, which generalize Chen’s, Lin’s, and Pearn’s indices C″_p, C″_pk, C″_pm, and C″_mk, defined for the case of only one variable with asymmetric tolerances, as well as the C_{_p}, C_{_pk}, C_{_pm}, and C_{_pmk} indices, defined by Grau for the case of several variables with symmetrical tolerances.

Key Words:

• Multivariate asymmetrical process capability indices
• multivariate process capability performance
• multivariate process capability potential
• rectangular solid region

Additional information

Notes on contributors

Daniel Grau

Daniel Grau Associate Professor in Statistics in University of Pau in the Business/Management Department as well as the Statistics Department. His research interests concern quality control.