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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CLSI document EPA2 describes the protocols q2 should be undertaken by the user to verify precision claims by a manufacturer. Summing the square of the differences gives a total of 0.

If an outlier is found the pair should be rejected and e0p5 cause investigated and resolved before repeating the run. This article has been cited by other articles in PMC.

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Evaluating Assay Precision

You may delete a document from your Alert Profile at any time. There is some variation in the terminology used but for the purposes of this discussion, repeatability, also known as within-run precision, is defined as the closeness of agreement between results of successive measurements obtained under identical conditions.

Summary When evaluating the precision of a method it is necessary to assess the repeatability within-run and the total or within-laboratory precision. If this is true then using the principle of analysis of variance components: Proceed to Checkout Continue Shopping. The following example relates to the verification of performance of calcium according to EPA2 using a five day protocol. Repeatability Repeatability is estimated using the equation below. Journal List Clin Biochem Rev v.


The first step is to calculate the mean of the replicates for each day, then for each result subtract the mean for that day and square the resultant value. When undertaking the assessment the data must be assessed for outliers, which are considered to be present if the absolute difference between replicates exceeds 5.

Note that we can’t provide technical support on individual packages. Using the example data and assuming the claimed repeatability is an improbable Pe05 of 1.

Description Usage Format References. Note, some authors refer to total variation as just the between-run component instead of combined between-run and within-run shown above.

As alluded to above, EPA2 is generally used to verify that a method is performing as is claimed by the manufacturer. If the document is revised or amended, you will be notified by email.

Repeatability Verification Value In order to compare the estimated repeatability to a claimed value we can calculate the critical el05 verification value using the equation: I have a suggestion. Already Subscribed to this document. On day 1 the mean of the three replicates was 1. We have no amendments or corrections for this standard. Instead total precision within a laboratory within-laboratory precision will be assessed.

Evaluating Assay Precision

However, for a method developed in-house a higher level of proof is required to validate the method, in which case EPA2 would be the appropriate guideline to use. NCCLS document EP5-A2, Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline – Second Edition provides guidance and procedures for ep005 the precision of in vitro diagnostic devices and includes recommendations for manufacturers in evaluating their devices and methods when establishing performance claims.


For example, on day 1 the average of the three values is 2. T is best calculated in a spreadsheet and is given by:. Care must be taken in knowing which term is being referred to.

In order to compare the estimated repeatability to a claimed value we can calculate the critical or verification value e05 the equation:. Add the following code to your website. This standard is not included in any packages. Similarly the within-laboratory a22 is estimated by measuring a sample 20 times over multiple days. While the term precision relates to the concept of variation around a central value, imprecision is actually what is measured.

Subscription pricing is determined by: 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. We want your feedback!