Moving XBar chart calculations

XBar-S chart control limits are calculated as follows:

Moving XBar chart calculations


Control Limits calculated from

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

If subgroup
size = 1


If subgroup
size >1 and


same as subgroup size = 1

If subgroup
size >25


same as subgroup size = 1

NOTE: For the Moving XBar chart, control limit values are variable for the first set of subgroups (the number is equal to the moving length). After the first set of subgroups the control limit values are constant. If control limits are specified for the Moving XBar chart, then the specified limits are constant and the system will calculate the initial variable control limit.

NOTE: For ith subgroups, where i<w, use i instead of w in the above formulae.

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

See Also

Quality Chart Formula Reference

Moving XBar chart

Moving XBar chart properties

Configuring a Moving XBar chart

XBar chart

Moving Range chart