Capability Analysis (Normal Distribution) - Estimation of Standard deviation
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Stat > Quality Tools > Capability Analysis > Normal > Estimate

Controls number of observations used in estimating standard deviation.

You can set preferences for the estimation of s using Tools > Options > Control Charts and Quality Tools > Estimating Sigma.

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Methods of estimating standard deviation

(for subgroup size > 1):

Rbar: Choose to estimate standard deviation using the average of the subgroup ranges.

Sbar: Choose to estimate standard deviation using the average of the subgroup standard deviations.

Pooled standard deviation: Choose to estimate 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.

(for subgroup size = 1): Minitab generally estimates standard deviation using the sample standard deviations or ranges of each subgroup. But when the subgroup size is 1 you cannot calculate sample standard deviations or ranges. Minitab estimates standard deviation using moving ranges instead.

Average moving range: Choose to estimate standard deviation using the average of the moving range.

Median moving range: Choose to estimate standard deviation using the median of the moving range.

Square root of MSSD: Choose to estimate 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.