Repeatability, Reproducibility, and Cooperative Tests

Without going too deeply into details we will refer to cooperative tests ( round robins , interlaboratory comparisons) in which two basic aims are  

Participation in cooperative tests is an important means of external quality assurance. 

With the respective degrees of freedomfrepeat andfrepmd both quantities are defined as repeatability  

In the case of m laboratories with ny(j l.m) measurements each the variances are computed according to  

Let us again use our previous case. In principle this example is void because of the widely different numbers of replicates. 

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