Methods for Estimating the Standard Deviation

BOXCHART Statement

Methods for Estimating the Standard Deviation

When control limits are computed from the input data, three methods (referred to as default, MVLUE and RMSDF) are available for estimating the process standard deviation $\sigma$ .The method depends on whether you specify the STDDEVIATIONS option. If you specify this option, $\sigma$ is estimated using subgroup standard deviations, and otherwise, $\sigma$ is estimated using subgroup ranges. For further details and formulas, see "Methods for Estimating the Standard Deviation" .

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