A method to estimate the uncertainty of measurements in a conglomerate of instruments/laboratories

A comparison of the performance, at two concentrations, of the measurement procedures for 23 common components is presented. For each component the within-, pure between- and total variations have been calculated and an imprecision profile indicated. Thus a pragmatic, readily and generally applicable method is advised to describe the performance of laboratories under repeatability and reproducibility conditions. The calculated total variation is compared with the results estimated from the biological variation of the properties. In most cases the within- laboratory variation is better than that given by the reference database, whereas in about half of the procedures the total variation exceeds that of the reference database. The outcome illustrates the transferability problems that multicentre studies and the diagnosis of patients face by measuring samples using a conglomerate of instruments/laboratories that are not aligned. The calculation procedures are detailed in an appendix and the calculation and presentation of the results are made with a custom-made worksheet program.