Defining Variables for Hotelling T-Square (Individuals) Chart - Specs Tab

Select the Specs tab of the Defining Variables for Hotelling T-Square (Individuals) 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) are used in the computations to construct the chart. By default, the statistics (means, variances/covariances) are computed from the data.

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

Option Description
Mean vector Displays a General User Entry Spreadsheet. Specify the means (center line values) for the variables selected for the chart. The multivariate chart is constructed based on the means entered, instead of means computed from the data. For more details, see Multivariate QC Computational Details.
Variance covariance matrix Displays a General User Entry Spreadsheet. Specify the variance/covariance matrix (sigma values) for the variables selected in the chart. The multivariate chart is constructed based on the variance/covariance matrix entered here, instead of the matrix computed from the data. For more details, see Multivariate QC Computational Details.