Sigma Estimator
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Six Sigma > Design for Manufacturability > Calculate Gap Pools > Sigma Estimator

If any of the standard deviations are missing, for each missing element standard deviation you must either:

·    Choose one of three methods to estimate the standard deviation(s); or

·    Enter a value.

Minitab stores the assigned standard deviations in the worksheet.

Note

You can easily re-estimate the standard deviations using a different method, if necessary. Simply scroll through the worksheet, putting back missing value symbols (*) for any standard deviations you want to re-estimate. Then, when you recalculate the gap pools, Minitab opens the Sigma Estimator dialog box, as before.

Dialog box items

Use upper confidence limit of: Enter an upper confidence limit for the element. To see how the standard deviation is calculated, see Estimating sigma.

Confidence level: Choose a confidence level of 80, 90, 95, or 99.

Use lower confidence limit of: Enter a lower confidence limit for the element. To see how the standard deviation is calculated, see Estimating sigma.

Confidence level: Choose a confidence level of 80, 90, 95, or 99.

Use expected range (estimate will be range/6): Enter an expected range for the element. Minitab assumes that the range is roughly equal to 6s, so dividing by 6 provides an estimate of s.

Specify a value: Enter a value for the standard deviation.