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A Multivariate Subgroup Rationality Test

Summary: [This abstract is based on the authors' abstract.] An aggregated measure for confirming rationality of the subgroups in multivariate control charts is expanded to confirm the rationality of each subgroup used in the charts. The proposed test uses statistical process control methods to maintain the time sequence of the data and is based on a test for equality of two covariance matrices. A second matrix used is the multivariate mean square successive difference covariance matrix. When differences between the two matrices indicate the lack of rationality of the corresponding subgroups, test results can be plotted on a control chart to determine the cause of the nonrationality. Two examples of the proposed method are given.

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  • Topics: Statistical Process Control (SPC)
  • Keywords: Covariance,Mean square errors (MSE),T2 control chart,Statistical process control (SPC),Multivariate analysis
  • Author: Holmes, Donald S.; Mergen, Erhan
  • Journal: Quality Engineering