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Second edition, 2019, Eurachem/EUROLAB/CITAC/Nordtest/AMC guide. Editorial page gives Michael H Ramsey, Stephen L R Ellison and Peter Rostron as editors; the 2019 citation uses M H Ramsey, S L R Ellison and P Rostron. Sections 9.3–9.5, printed pp. 16–22, give nested variance components, duplicate sampling and duplicate chemical analysis. Section 9.4.2 and Figure 2 distinguish sampling replication from analytical replication and warn that one-sampler duplicates do not determine sampling bias.

Section 9.4.2, Note 2 and Figure 2, printed p. 19 (PDF p. 29), explain an unbalanced duplicate design. Appendix D.2 and Figure D.2(b), printed p. 103 (PDF p. 113), show two analyses of one collected sample and one analysis of its field duplicate, retaining sampling and analytical variance-component estimation. This differs from the simplified balanced design in Figure D.2(a), which omits analytical duplicates.