ESTIMATION OF VARIANCE-COMPONENTS FROM THE RESULTS OF INTERLABORATORYCOMPARISONS

Interlaboratory comparisons are frequently carried out in analytical l aboratories either as a part of their quality assurance procedures or as an important part of analytical method development. The total analy tical error is usually composed of three components: the random measur ement error, laboratory bias and sample-laboratory interaction. The si gnificance of these error components and the estimates of their varian ces can in principle be obtained from a properly designed experiment b y carrying out the analysis of variance. If the samples used in the in terlaboratory comparison cover a wide concentration range it is usual that the errors are not independent of concentration and, consequently , the estimation of all three error components is difficult. In this p aper a seating procedure for the initial data is proposed that makes i t possible to estimate all three error components.