EP5-A2. ISBN Volume 24 Number ISSN Evaluation of Precision Performance of Quantitative Measurement. Methods; Approved. Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline, EP05A2E. Clinical and Laboratory Standards Institute (CLSI) document EPA2 describes the protocols for determining the precision of a method. The precision of a.

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The contents of articles or advertisements in The Clinical Biochemist — Reviews are not to be construed as official statements, evaluations or endorsements by the AACB, its official bodies or its agents. If this is true then using the principle of analysis of variance components: CLSI now a22 the term within-laboratory precision to denote the total precision within the same facility using the same equipment 1 and this term will be used for this concept throughout this paper.

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Evaluating Assay Precision

If QC material is being used for fp05 precision assessment, it should be different to that used to control the assay. EPA2 should be used to validate a method against user requirements, and is generally used by reagent and instrument suppliers to demonstrate the q2 of their methods.

Each level is run in duplicate, with two runs per day over 20 days, and each run separated by a minimum of two hours. Summary When evaluating the precision of a method it is necessary to assess the repeatability within-run x2 the total or within-laboratory precision.

Estimation of Repeatability and Within-Laboratory Precision The following example relates to the verification of performance of calcium according to EPA2 using a five day protocol. Unfortunately this approach is insufficient, as it tends to under-estimate repeatability, as the operating conditions in effect at the time may not reflect usual operating parameters.


Need more than one copy? On 20 days two separate runs with two replicates of the same sample are measured.

As the period of assessment is quite short, the total SD or within-laboratory SD derived from these experiments should not generally be used to define acceptability limits for internal quality control. Similarly the within-laboratory precision is estimated by measuring a sample 20 times over multiple days.

Precision claims by a manufacturer should be tested at at-least two levels, epp05 running three replicates over five days. When using quality control samples, these should be different to those used to ensure the instrument is in control at the time of the assessment. This standard is not included in any packages. However, for a method developed in-house a higher level of proof is required to e05 the method, in which case EPA2 would be the appropriate guideline to use.

Evaluating Assay Precision

s2 Add the following code to your eep05. Thus we need to find the CLSI document EPA2 describes the protocols that should be undertaken by the user to verify precision claims by a manufacturer.

Dr Douglas Chesher e-mail: Included are guidelines for the duration, w2, materials, data summaries, and interpretation techniques that are adaptable for the widest possible range of analytes and device complexity.

National Center for Biotechnology InformationU. This article has been cited by other articles in PMC. We have no amendments or corrections for this standard. You may delete a document from your Alert Profile at any time. Evaluation of Results As alluded to above, EPA2 is generally used to verify that a method is performing as is claimed by the manufacturer.


Care must be taken in knowing which term is being referred to. Support Center Support Center. Standards Subsctiption may be the perfect solution. Summing the square of the differences gives a total of 0. For the purposes of this example the eep05 of only a single level are shown Table 1.

Australasian Association of Clinical Biochemists Website. The next step is to calculate epp05 variance for the daily means s b 2 using the equation. The procedures are designed for manufacturers or developers of clinical laboratory measurement methods, and for users of those methods who wish to determine their own performance capabilities or to verify claims from a manufacturer.

Linnet K, Boyd JC. Please first verify your email before subscribing to alerts. Subscription pricing is determined by: For a normal distribution the measure of imprecision is the standard deviation SD. The page or its content looks wrong. Evaluation of precision performance of quantitative measurement methods.

Embedding an R snippet on your website. R Package Documentation rdrr. Reproducibility is at the other extreme and refers to the closeness of agreement between results of successive measurements obtained under changed conditions time, operators, calibrators, reagents, and laboratory. Note, some authors refer to total variation as just the between-run component instead of combined between-run and within-run shown above.