Enter the historical value for the parameters that Minitab uses to calculate the center line and control limits. If you do not enter values, Minitab estimates the mean and covariance matrix from the data.
- You can enter a mean for each variable. If the means are in columns, enter one column per variable. If you have stages, enter a list of constants for the stages for each variable.
- Covariance matrix
- You can enter one or more matrices for estimating the covariance matrix. Each matrix must be a positive definite square matrix with the same number of rows and columns as columns of data. The elements on the matrix diagonal must be positive. Element (i,j) must equal element (j,i). If you enter only one matrix, all stages use that covariance matrix; otherwise, enter a matrix for each stage.
- Number of samples used to calculate covariance
- After verifying that your process is in control, enter the number of samples you used to estimate the historical parameters. If you entered more than one covariance matrix, enter the corresponding number of samples used for each matrix.