Monitoring bivariate processes with synthetic control charts based on sample ranges

Abstract The RMAX chart was proposed to control the covariance matrix of two quality characteristics. monitoring statistic is maximum standardized sample ranges from bivariate observations In this article, we investigate performance synthetic charts. first signals when a second point, not far one, falls beyond warning limit. additionally point charts are compared with standard and generalized variance S chart. best option detect moderate or even small changes in matrix. To large matrix, additional run rules necessary.