Microsoft Word - BYLAWS 9_26_10

OMB MEETING MATERIALS

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Straw Man: This document is a starting point for future drafts and is not an approved document. Please do not distribute to laboratory staff for use.

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7.6

Evaluation of measurement uncertainty

7.6.1

Note: It is important for the laboratory to understand what the major factors of uncertainty are and provide appropriate control for all such factors. Refer to Eurachem/CITAC guide CG4: Quantifying Uncertainty in Analytical Measurement , OECD Principles on Good Laboratory Practice , and the WHO Handbook: Good Laboratory Practice (GLP) Quality Practices for Regulated Non-Clinical Research and Development for additional information.

7.6.3

Note: ISO/IEC Guide 98-3 Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) provides the current international consensus method for estimating measurement uncertainty. There are three main categories of uncertainty in life science testing laboratories: qualitative test methods, semi-quantitative test methods, and quantitative test methods. Note: Uncertainty of measurement can be estimated using quality control data, such as the analysis of reference materials. The standard deviation of data points is multiplied by the uncertainty coverage factor, k , obtained from the Student t -tables. At least 20 data points should be used, though it can be calculated using fewer points, as long as the appropriate coverage factor is used. If using this approach, the laboratory shall demonstrate that all uncertainty components which are of importance in the given situation have been taken into account, such as sampling which may not be a component in the uncertainty estimated from the analysis of reference materials. In some cases, matrix or analyte specific estimates of measurement uncertainty may need to be calculated. Method validation data, if available and appropriate, may be used to estimate uncertainty of measurement. Depending on the test method and the accrediting body, in the case of collaboratively studied methods, the reproducibility may be used to estimate the uncertainty. procedures shall include the use of quality control materials, in order to demonstrate that the test worked properly. For enumeration assays, a quantified quality control material shall be used. A quality control material may include, but is not limited to, certified reference materials (CRMs), reference materials (RMs), replicate analyses, positive/negative control samples, laboratory control samples (LCSs), blanks, and matrix spikes. In the absence of any CRM or RM the laboratory shall do its best to obtain a material with some limited consensus of accuracy (e.g., by subjecting material to multiple methods or analyses in-house, sharing material with another laboratory to determine an average result, etc.). The suitability of the quality control material used shall be justified by the laboratory. When testing for pathogens or select agents, a quality control material that contains a surrogate analyte may be used. 7.7 Ensuring the validity of results 7.7.1 Quality control procedures shall be defined for both quantitative and qualitative methods. These

A quality control material shall be used with each batch of samples analyzed. The laboratory shall define and justify what constitutes a batch of samples.

Note: Some laboratories use the term "batches"; other laboratories may use the terms “run” or "lot" or “runs”. Any term is acceptable; but, the laboratory must define the term unambiguously.

Method precision shall be periodically evaluated by the laboratory. This may be accomplished by evaluating quality control material data over time using appropriate statistical process control (SPC) techniques. Duplicate or replicate analyses of a CRM/RM, positive samples, matrix spikes, LCSs, or reference materials can also be used.

08/09/2018