Capability Analysis (Between/Within) -
Estimation of Standard Deviationmain topic see also
Capability Analysis (Between/Within) -
Estimation of Standard DeviationStat > Quality Tools > Capability Analysis > Between/Within > Estimate
Use to control the method for estimating within and between standard deviation.
You can set preferences for the estimation of s using Tools > Options > Control Charts and Quality Tools > Estimating Standard Deviation.
Methods of estimating standard deviation
Within subgroup
Rbar: Choose to estimate within-subgroup standard deviation using the average of the subgroup ranges.
Sbar: Choose to estimate within-subgroup standard deviation using the average of the subgroup standard deviations.
Pooled standard deviation: Choose to estimate within-subgroup standard deviation using a pooled standard deviation.
Use unbiasing constants: Uncheck to estimate within-subgroup standard deviation not using unbiasing constants. The default is to use the unbiasing constants.
Between subgroups
Average moving range: Choose to estimate between-subgroups standard deviation using the average of the moving range.
Median moving range: Choose to estimate between-subgroups standard deviation using the median of the moving range.
Square root of MSSD: Choose to estimate between-subgroups standard deviation using the mean squared successive differences.
Use moving range of length: Choose to enter the number of observations used to calculate the moving range. By default, a span of 2 is used as consecutive values have the greatest chance of being alike. The span must be < 100.
Use unbiasing constants to calculate overall standard deviation: Check to estimate the overall standard deviation using unbiasing constants. The default is to not use the unbiasing constants.