What are the Westgard rules and how should they be used to assess quality control results?

“Westgard rules” are generally used with 2 or 4 control measurements per run, which means they are appropriate when two different control materials are measured 1 or 2 times per material, which is the case in many chemistry applications.

How do you implement Westgard rules in a lab?

Best Practices for “Westgard Rules”

1. Define the quality that is needed for each test.
2. Know the performance of your method (CV, bias).
3. Calculate the Sigma-metric of your testing process.
4. Relate the QC procedure for the test to the Sigma-performance of the method.

What are the control limits of a Levey-Jennings chart?

In many laboratories, this rule is used to reject a run when a single control measurement exceeds a 2s control limit. 13s corresponds to a Levey-Jennings chart having control limits set as the mean plus/minus 3s. An analytical run is rejected when a single control measurement exceeds a 3s control limit.

What is the purpose of a Levey Jennings chart?

A Levey–Jennings chart is a graph that quality control data is plotted on to give a visual indication whether a laboratory test is working well. The distance from the mean is measured in standard deviations.

What are QC rules?

Westgard Rules are multirule QC rules to help analyze whether or not an analytical run is in-control or out-of-control. It uses a combination of decision criteria, usually 5 different control rules to judge the acceptability of an analytical run.

What is the Westgard multi rules?

What are Westgard Rules? Westgard Rules are multirule QC rules to help analyze whether or not an analytical run is in-control or out-of-control. It uses a combination of decision criteria, usually 5 different control rules to judge the acceptability of an analytical run.

How do you plot values in Levey Jennings chart?

Plot the center line as a sold line on the Levey-Jennings chart and label. Plot the control limits on the Levey-Jennings chart and label. If you are using the Westgard rules (described below), you will also need to plot the lines at +1s, +2s, -1s and -2s from the center line.

How do you do a Levey Jennings chart?

Here are the steps to create a Levey Jennings Chart using QI Macros:

1. Click and drag over your data to select it.
2. Next, click on the QI Macros menu > Control Charts (SPC) > Special (CUSUM, EWMA) and then on the type of Levey Jennings Chart you want.

When to reject a run on a Levey Jennings chart?

1 2s refers to the control rule that is commonly used with a Levey-Jennings chart when the control limits are set as the mean plus/minus 2s. In many laboratories, this rule is used to reject a run when a single control measurement exceeds a 2s control limit.

What are the control values for Levey Jennings QC?

You can print the Levey-Jennings QC Practice Exercise (below) to obtain a worksheet that shows all these control results. For day 1, the value for Control 1 is 200 and Control 2 is 247.

When to use the 12s rule in Levey Jennings?

12s refers to the control rule that is commonly used with a Levey-Jennings chart when the control limits are set as the mean plus/minus 2s. In the original Westgard multirule QC procedure, this rule is used as a warning rule to trigger careful inspection of the control data by the following rejection rules.

Who is the author of the Levey Jennings control chart?

Patricia L. Barry, co-author of Cost-Effective Quality Control: Managing the Quality and Productivity of Analytical Processes, provides a primer on how to construct, use, and interpret the Levey-Jennings chart. Please Note: This article is from the first edition.