(inter-batch/lot precision)

 Guidelines - Uncertainty of Measurement 28.49 Kb

Parameter of Uncertainty of Measurement to be assessed = expanded uncertainty

• = Standard Deviation (SD) x 2 (rather than Coefficient of Variation [CV] x 2)
• Note: CV = (SD / Mean) x 100%

Number of measurements

• At least 60 (degrees of freedom), so at least n=61 measurements
• Across different lots/batches What tests does this apply to?
• any test where quantitative values are used to obtain the result, including qualitative assays where a quantitative value is used to generate a test result (eg. Anti-ENA ELISA)

Reference material

• any external reference material (commercial or pooled patient samples) used for each assay
• value should be close to the cut off, clinical decision points OR mid range where curve is linear
• the kit controls should not be used instead of external reference material, as the assessment will be across different lots/batches

Reporting

• At present, we would not advise including the expanded uncertainty parameter on the report

Limitations

• We acknowledge the above expanded uncertainty parameter does not take into account bias or accuracy.

Last updated January 2005