Defining Variables for MEWMA (Means) Chart - Specs Tab

Select the Specs tab of the Defining Variables for MEWMA (Means) Chart dialog box to access options to specify a mean vector and/or variance/covariance matrix for the multivariate chart. If specified from this tab, these values (mean vector, and/or variance/covariance matrix) will be used in the computations to construct the chart. By default, these statistics (means, variances/covariances) are computed from the data.

These options are useful in order to specify standard values (means, etc.) from previous charting as the standard against which to chart new samples (observations).

Element Name Description
Mean vector Click this button to display a General User Entry Spreadsheet. Specify here the means ("center line" values) for the variables selected for the chart. The multivariate chart will be constructed based on the means entered here, instead of means computed from the data (see Multivariate QC Computational Details for computational formulas).
Variance covariance matrix Click this button to display a General User Entry Spreadsheet. Specify here the variance/covariance matrix ("sigma" values) for the variables selected in for the chart. The multivariate chart will be constructed based on the variance/covariance matrix entered here, instead of the matrix computed from the data (see Multivariate QC Computational Details for computational formulas).