1- & 2- precision over days, CLSI-EP5. This procedure is available in the Analyse -it Method Evaluation edition. Precision determines the variation of a method. NCCLS document EP5-A2 (ISBN ). NCCLS, West Valley Road, Suite , Wayne, Pennsylvania USA, THE NCCLS . Buy CLSI EP5 A2 Ed. 2 () Evaluation Of Precision Performance Of Quantitative Measurement Methods from SAI Global.

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Sometimes the manufacturer identifies the comparative measurement vlsi only generically. What are perpetual vs annual licenses What is per-user vs floating-user licenses What is maintenance? Within-Laboratory Precision Finally, we can calculate the total or within-laboratory SD s l using the equation: When entering new data we recommend using New Dataset to create a new precision dataset. Verification of Precision EP15 first describes a precision verification experiment.

CLSI EP5 1- & 2- run precision | Analyse-it®

Australasian Association of Clinical Biochemists Website. The dataset must contain at least two continuous scale variables containing e;5 observations in replicate for a run of the method.

Journal List Clin Biochem Rev v. Author information Copyright and License information Disclaimer. Comparing against an imprecision goal specification Total precision within device or laboratory can be compared against a performance goal.

If the sample materials are appropriate, and target concentrations are available, the user can estimate the bias between the mean concentration calculated in the clwi experiment relative to the target concentration of each of the materials.

This is valuable when the user wishes to verify precision and to estimate bias relative to a peer group or target concentration. On day 1 the mean of the three replicates was 1.

Evaluating Assay Precision

If the p-value is significant the observed precision is outside the goal. Evaluation of Results As alluded to above, EPA2 is generally used to verify that el5 method is performing as is claimed by the manufacturer.


Goal total precision, calculated from the imprecision specification and the concentration level, and a hypothesis test to test if the observed precision is cldi the goal are shown.

Repeatability Repeatability is estimated using the equation below. The choice of material depends on the purpose of the user in estimating the bias.

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.

A spreadsheet for assisting with the calculations described in this article is available from the AACB web-site. If an outlier is found the pair should be rejected and the cause investigated and resolved before repeating the run. This is its fourth iteration, and although it retains much of its original approach, there were some significant changes in the A3 version.

For example, if the true standard deviations were lcsi exactly equal to their claimed counterparts, the calculated standard deviations would exceed their published counterparts fifty percent of the time in verification experiments.

Elsevier Saunders; St Louis: Latest blog post Analyse-it 5. The figure of 5. For bias relative to the quality control peer group, quality control materials with peer group values for the measurement procedure are appropriate. However, for a method developed in-house a higher level of proof is required to validate the method, in csli case EPA2 would be the appropriate guideline to use. National Center for Biotechnology InformationU.

The assessment is performed on at least two levels, as precision can differ over the analytical range of an assay.

Using the test To start the test: Support Center Support Center. Sometimes the calculated standard deviations may exceed the published values, and yet the true standard deviations are less than the published values.

Please review our privacy policy. If this is true then using the principle of analysis of variance components: 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.


Similarly the within-laboratory precision is estimated by measuring a sample 20 times over clxi days. A method measured on a continuous scale over a number of days, with one or two runs per day. Patient samples or control materials which have been repeatedly assayed with a measurement procedure felt to be substantially equivalent to the measurement procedure being evaluated may be appropriate if the user is interested in estimating bias relative to that measurement procedure.

Enter Pre-assigned concentration of the analyte, if known. Evaluation of precision performance of quantitative measurement methods. Statements of opinion in AACB publications are those of the contributors. Select any cell in the range eep5 the dataset to analyse, then click Precision on the Analyse-it tab, then click 1 and 2 Run over Days. Precision should be tested with two or more sample materials at different medical decision point concentrations.

Evaluating Assay Precision

Download latest release Version 5. The next step is to calculate the variance for the daily means s b 2 using the equation. The EPA2 protocol is similar except that the experiment is undertaken with three replicates over five days for at least two levels. Click OK to run the test. All blog posts Subscribe to blog updates. Repeatability Verification Value In order to compare the estimated repeatability to a claimed value we can calculate the critical or verification value using the equation: If this is true then using the principle of analysis of variance components:.

If the calculated standard deviations are less than the published values, the user has verified the claim.