Trying to Create Levey Jennings 10-20-30% Charts in Excel?

QI Macros can create them for you!

Draw a Levey Jennings Percent Chart using QI Macros

Select your data.
Click on QI Macros menu > Control Charts (SPC) > Special > Levey Jennings % .
QI Macros will do the math and draw the graph for you.

The Levey Jennings Percent chart uses 10% of the Average to Calculate Control Limits

Healthcare labs use the Levey Jennings Charts to monitor key measures of health like cholesterol and glucose. The Levey Jennings Chart, unlike other SPC charts, has an option to use 10 percent of the average as a way of calculating control limits:

levey jennings percent control chart in Excel

How to Change the Percentage Used

Once the chart is created, you can click on the data sheet created when the macro was run and change the percentage (in cell I1) to 5% or whatever you desire:

change percent in levey jennings percent chart

QI Macros will update the chart with new control limits. Note: Use the QI Macros chart menu to re-rerun stablility analysis with the new limits. You may also want to adjust the scale of the y-axis:

levey jennings change percent

According to SOFT / AAFS FORENSIC TOXICOLOGY LABORATORY GUIDELINES 9.1.12, standard deviation may represent an unacceptably large percentage deviation from the mean. Therefore, a realistic percentage deviation should be used, such as ±20% or ±30%.