A run is rejected when a single control measurement exceeds the mean plus 3s or the mean minus 3s control limit”ġ1 22s Rule “22s reject when 2 consecutive control measurements exceed the same mean plus 2s or the same mean minus 2s control limit.”ġ2 41s Rule “41s - reject when 4 consecutive control measurements exceed the same mean plus 1s or the same mean minus 1s control limit.”ġ3 R4s Rule “R4s - reject when 1 control measurement in a group exceeds the mean plus 2s and another exceeds the mean minus 2s. ”ġ0 13sRule “13s refers to a control rule that is commonly used with a Levey-Jennings chart when the control limits are set as the mean plus 3s and the mean minus 3s. 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. “12srefers 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. Standard deviation = quantity expressing by how much the members of a group differ from the mean value for the groupġ-collect your control measurements 2- Find mean and Standard deviation 3- Draw (+3,, 0, -1, -2, -3) lines on the Levey-Jennings chartĨ 12s Rule 1= one point 2S= position exceeds 2S To calculate: Just add up all the numbers, then divide by how many numbers there are. Mean= the average of the numbers: a calculated "central" value of a set of numbers. Westgard rules are used to define specific performance limits for a particular assay and can be used to detect both random and systematic errors. Westgard rules are commonly used to analyse data in Shewhart control charts. Presentation on theme: "Westgard rules."- Presentation transcript:Ģ To assure that our tests results are correct, we run control materials.īased on the control material, we decide whether our results are acceptable.ģ What is Multirule QC? “Multirule QC uses a combination of decision criteria, or control rules, to decide whether an analytical run is in-control or out-of-control” In-control = acceptable Out-of-control= unacceptable “The advantages of multirule QC procedures are that false rejection can be kept low while at the same time maintaining high error detection.”Ĥ Westgard rules The formulation of Westgard rules were based on statistical methods.
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