Laney u' Chart | u Prime Charts in Excel

The purpose of a u chart is to determine stability of "counted" data (e.g., errors per bill, dents in a car door, etc.) when there can be more than one defect per unit and the sample size varies.

The u chart works for most data sets. However, if your data meets certain criteria you may need to consider an XmR chart or a Laney u' Chart (u Prime).

Consider an XmR chart if the denominator does not vary widely from sample to sample and your u chart looks like the one below where the control limits seem too narrow for the data and most points are highlighted as unstable.

compare u chart to laney u chart

Here is an XmR Individuals chart run on the same data:

xmr chart compare to laney u chart

Consider a Laney u' Chart (u Prime) if: the sample sizes in your denominator vary greatly.

A Laney u' Chart (u Prime) will have wider control limits than the u chart and it will have varying control limits that may help identify unstable points not identified by the XmR chart. Here is a Laney u' Chart of the same data.

laney u chart

QI Macros add-in for Excel contains a Laney u' Chart template. Click on QI Macros > Control Chart Templates > Attribute (c,np,p,u,g,t) > u Chart to open up the u Chart template. Then click on the U' Chart Skyline tab at the bottom to open up the Laney u' Chart (u Prime) template.

u-chart-template-tabs

Change the Y-Axis Multiplier:

  • Located to the right of the chart, this functionality allows you to change the multiplier. This automatically changes the y-axis value (e.g. 1, 10, 100, etc.):

y-axis-multiplier

Toggle Between u Chart and u' Chart:

  • Specifically offered in the u Chart macro, you can toggle between a u Chart and a u' Chart by inputting either "False" (u Chart) or "True" (u' Chart). This option is located to the right of your chart:

p-prime-toggle

Learn More...

Why Choose QI Macros Over Other Control Chart Software?

affordable

Affordable

  • Only $299 USD - less with quantity discounts
  • No annual subscription fees
  • Free technical support

easy to use

Easy to Use

  • Works right in Excel
  • Create a chart in seconds
  • Easy to customize & share charts

proven and trusted

Proven and Trusted

  • More than 100,000 users
  • In More than 80 countries
  • Five Star CNET Rating - Virus free
Data Mining and Analysis
Download Free QI Macros Trial
Buy QI Macros for Excel Now