# Need to create a Laney u' Chart | u Prime Chart in Excel?

## QI Macros can draw one for you in seconds!

#### Draw a u' Chart using QI Macros

1. Select your data.
2. Click on QI Macros menu > Control Charts (SPC) > Attribute> u' Laney.
3. QI Macros will do the math and draw the graph for you.

### When should you use a laney u' chart?

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 will work 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 control limits seem too narrow for the data and most points are highlighted as unstable. See below example.
• Consider a Laney u' Chart (u Prime) if: the sample sizes in your denominator are large and vary greatly.

### Compare a u chart to an XmR chart on the same data

The control limits on this u chart seem too narrow for the data and all points are considered unstable.

Here is an XmR Chart run on the same data:

### Laney u' chart on the same data

A Laney u' Chart 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.

### 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:

### Laney u' Chart Ready Made Template

QI Macros also contains a Laney u' Chart template. Open it by clicking QI Macros > Control Chart Templates > Attribute > 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 (p Prime) template.