Comparison of three multivariate process capability indices

Process capability analysis often entails characterizing or assessing processes or products based on more than one engineering specification or quality characteristic. When these variables are related characteristics, the analysis should be based on a multivariate statistical technique. In this expository paper, three recently proposed multivariate methodologies for assessing capability are contrasted and compared. Through the use of several graphical and computational examples, the information summarized by these methodologies is illustrated and their usefulness is discussed.