Laney u' Chart (u Prime) Formulas
The Laney u' Chart (u' Chart or modified u Chart) works much like an XmR Chart.
- Convert the p values to z values.
- Calculate the moving range of the z values.
- Use these values to calculate sigma-estimator.
- Use the sigma estimator to adjust the control limits.
Here are the formulas used to calculate a Laney u' Chart (u Prime):
Source: Improved Control Charts for Attributes, David B. Laney © 2002
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