Stephen L. R. Ellison

Steven L. R. Ellison is the name printed for an analytical chemistry coauthor of the recovery-information report, with an affiliation at the Laboratory of the Government Chemist in Teddington. Eurachem's later organizer biography identifies the same report among the works of Stephen L. R. Ellison, an LGC Fellow specializing in analytical statistics and measurement uncertainty.^[ref][ref]

The Eurachem biography also identifies him as a principal author of Quantifying Uncertainty in Analytical Measurement and a coauthor of method-validation and laboratory-proficiency-testing guidance. This work develops the statistical interpretation needed to compare analytical results under stated conditions.^[ref]

For an original illustration, two independent uncertainty contributions of $0.30$ and $0.40\mathrm{mg}$ combine to $0.50\mathrm{mg}$ in quadrature. If their correlation coefficient is 0.5 and both enter the model with positive sensitivity, the combined standard uncertainty is insteadThe model determines which inputs contribute and whether covariance matters. Listing more decimal places does not resolve an omitted source of uncertainty. This calculation illustrates the subject of the guidance; it is not experimental data attributed to Ellison.