Laney u' Chart (u Prime) Formulas

QI Macros Can Calculate Them For You!

Create a Laney u Chart using QI Macros

  1. Select your data.
  2. Select the chart on QI Macros menu.
  3. QI Macros will do the math and draw the graph for you.

Go Deeper:

The Laney u' Chart (u' Chart or modified u Chart) works much like an XmR Chart.

  1. Convert the p values to z values.
  2. Calculate the moving range of the z values.
  3. Use these values to calculate sigma-estimator.
  4. Use the sigma estimator to adjust the control limits.

Here are the formulas used to calculate a Laney u' Chart (u Prime):

laney u chart formula

Source: Improved Control Charts for Attributes, David B. Laney © 2002

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The Laney u' Chart (u Prime) is just one of the tools included in QI Macros SPC Software for Excel.

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