Methods and formulas for graphs in Normal Capability Sixpack

Histogram

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".

Probability plot

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

Charts

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