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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For the purposes of this discussion reproducibility will not be considered, as it involves multiple laboratories. T is best calculated in a spreadsheet and is given by:. Variance Component Analysis Description Usage Format References Description This data set consists of simulated measurements for an experiment conducted to evaluate the precision performance of measurement methods.

EPA2 should be used to validate a method against user requirements, and is generally used by reagent and instrument suppliers to demonstrate the precision of their methods. The eep05 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.

We have no amendments or corrections for this standard. 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. The next step is to calculate the variance for the daily means s b 2 using the equation. CLSI now uses 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.

Marginal Effects for Model Objects. Your Alert Profile lists the documents that will be monitored. 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 the repeatability and within-laboratory SD are less than that indicated by the manufacturer, then the user has demonstrated precision consistent with the claim and no further calculations are required.


If this is true then using the principle of analysis of variance components: These include pooled patient samples, quality control material, or commercial standard material with known values. 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.

The reader is referred to the CLSI documents for details. R Package Documentation rdrr. The EPA2 protocol is similar except that the experiment is undertaken with three replicates over five days for at least two levels. Dr Douglas Chesher e-mail: Acknowledgments Special thanks to Amanda Caswell for her careful review of the manuscript.

If QC material is being used for the precision assessment, it should be different to that used to control the assay. Table 3 shows the results of the same calculation for the remaining days. Description Usage Format References.

Evaluating Assay Precision

In order to compare the estimated repeatability to a claimed value we can calculate the critical or verification value using the equation:. Each level is run in duplicate, with two runs per day over 20 days, and each run separated by a minimum of two hours. Embedding an R snippet on your website. Estimation of Fp05 and Within-Laboratory Precision The following example relates to the verification of performance of calcium according to EPA2 using a five day protocol.

Evaluating Assay Precision

Add to Alert PDF. Instead total precision within a laboratory within-laboratory precision will be assessed.

National Center for Biotechnology InformationU. For n measurements we have:.

Introduction Part of the process of verifying or validating a method to confirm that it is suitable for use eo05 an assessment of precision. You can download and open this file to your own computer but DRM prevents opening this file on another computer, including a networked server. Support Center Support Center. This standard is also available to be included in Z2 Subscriptions.

Add the following code to your website. Note, some authors refer to total variation as just the between-run component instead of combined between-run and within-run shown above. Selection and analytical evaluation of ep0 with statistical techniques.


Subscription pricing is determined by: Open in w2 separate window. Finally, we can calculate the total or within-laboratory SD s l using the equation:. 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.

On 20 days two separate runs with two replicates of the same sample are measured. For a normal distribution the measure of imprecision is the standard deviation SD. However, if the values achieved are greater than those reported by the manufacturer, a statistical test needs to be performed to determine whether this difference is statistically significant. Author information Copyright and License information Disclaimer.

Table 2 shows the results of each of these calculations. Note that we can’t provide technical support on individual packages.

There should be at least one quality control QC sample in each run. I have a suggestion. Care must be taken in knowing which term is being referred to. Thus we need to find the Evaluation of Results As alluded to above, EPA2 is generally ep5 to verify that a method is performing as is claimed by the manufacturer.

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. ISSN — When evaluating the precision of an assay, the trivial approach for estimating repeatability for any given level is to perform 20 replicate analyses in a single run on a single day.