Course Content


10 - How to Select Control Rules



Laboratories must select appropriate QC rules based on the quality required for a test and the method’s observed accuracy and precision.  In this activity, participants are introduced to the Sigma-metrics QC Selection Tool, available at  Using a case scenario, participants will select appropriate QC rules and design a QC strategy for a workstation.

Key Message

  • The measurement procedure’s quality requirement and the accuracy and precision must be considered in the selection of appropriate QC rules.
  • The control rule selected should alert the laboratorian to a significant change before wrong results are reported.
  • Selected control rules should maximize the error detection (Ped ≥ 90%) and minimize the false rejection (Pfr ≤ 5%) while using the lowest number of control measurements possible.

Self Assessment

Can you: 

  • Select appropriate QC rules using the Sigma-metrics QC Selection Tool from the Westgard internet site?
  • Select a TEA% using the Westgard internet site?
  • Design an effective QC strategy for a workstation?