Testing precision against a performance claim

Test if the precision matches a performance claim.

You must have already completed the task:

Estimating the precision of a measurement system

You should use this procedure when you already have a performance claim from a manufacturer's package insert, and you want to test whether your precision is significantly greater than the claim. It is possible for the precision from a study to be greater than the claim, but for the difference to be due to the random error in your study.

Activate the analysis report worksheet.
On the Analyse-it ribbon tab, in the MSA group, click Test.
The analysis task pane Precision panel opens.
In the Hypothesized imprecision grid, alongside each level, enter the performance claim as the SD in measurement units or the CV as a percentage (suffix with % symbol).
Optional: In the Significance level edit box, type the maximum probability of rejecting the null hypothesis when in fact it is true (typically 5% or 1%) and if required select the Familywise error rate check box.

Note: CLSI EP15 uses a 5% familywise significance level so the overall significance level is a maximum of 5% regardless of the number of comparisons (for example, for 1 level the significance level is 5%, for 2 levels the significance level is 5%/2 = 2.5% for each level, for 3 levels the significance level is 5%/3 = 1.6% for each level).
Click Recalculate.

Related concepts

Precision

Related information

CLSI. (2014b). User Verification of Performance for Precision and Trueness (EP15-A3). Clinical and Laboratory Standards Institute.

Available in Analyse-it Editions
Method Validation edition
Ultimate edition