Enter historical parameters for Xbar Chart

Enter the historical values 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 the standard deviation from the data. If you enter only one value, Minitab estimates the other parameter from the data.

Mean

You can enter a single mean for the entire chart, or you can enter a mean for each stage. Minitab uses the mean to calculate the center line on the Xbar chart.

Standard deviation

You can enter a single standard deviation for the entire chart, or you can enter a standard deviation for each stage. Minitab uses the standard deviation to calculate the control limits on both charts and the center line on the S chart.