ABSTRACT
This chapter discusses PNC-based multivariate process capability indices (MPCIs) in detail. Capability Index is useful when the people try to relate the actual variability of the process with that of the admissible one. Hence, study of the relationship of the capability index with non-conforming proportion becomes important. Wang and Chu modified the proposed MPCI by dividing the variables into two broad groups: one set of variables which together follows multivariate normal distribution, and the other set of variables which does not follow multivariate normal distribution. Typically, a PCI compares the natural variability of a stable process and the allowed variability. The three MPCIs proposed are and being measures of process capability related to potential proportion of conforming and actual proportion of conforming, respectively, the two measures are related among themselves like Cp and in the univariate case.
