Methods and formulas for graphs in Normal Capability Sixpack

The histogram is displayed with two normal curves.

Black dashed curve

This normal distribution is generated using the process mean and the within-subgroup standard deviation.

Red solid curve

This normal distribution is generated using the process mean and the overall standard deviation.

For information on how the standard deviations are calculated, go to Methods and formulas for methods used in Normal Capability Analysis and click "Estimating standard deviation".

For information on the calculations used to create the normal probability plots, go to Methods and formulas for probability plot in Individual Distribution Identification.

For normal capability sixpack, Minitab displays different control charts depending on the subgroup size.

• If the subgroup size is 1, Minitab displays an I chart with an MR chart.

  For information on the methods used for the I chart, go to Methods and formulas for I chart.

  For information on the methods used for the MR chart, go to Methods and formulas for MR chart.

• If the subgroup size is greater than 1, Minitab displays an Xbar chart with an R or S chart.

  For information on the methods used for the Xbar chart, go to Methods and formulas for the Xbar chart in Xbar-R Chart.

  For information on the methods used for the R chart, go to Methods and formulas for the R chart in Xbar-R Chart.

  For information on the methods used for the S chart, go to Methods and formulas for S Chart.