XBar-S chart calculations

XBar-S chart control limits are calculated as follows:

XBar-S chart calculations


Control Limits calculated from

Control Limits calculated from
standard (mean ( ยต ) and/or
standard deviation (s ) are

XBar chart control limits


Sigma chart control limits


is calculated using subgroup standard deviations instead of subgroup ranges. For more information, see Estimated Sigma.


NOTE: If subgroup size is variable, m is replaced with mi for ith subgroup limits. When subgroup size is variable, the control limit values will not be the same; therefore, the chart may display `city skyline' type control lines.

Data Plot Items

Descriptive Statistics Displayed

See Also

Quality Chart Formula Reference

XBar-S chart

XBar-S chart properties

Configuring an XBar-S chart

XBar chart

Sigma chart

XBar-R chart