= Stephen L. R. Ellison
{c}
= Steven L. R. Ellison
{c}
{synonym}
<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 \b[Stephen L. R. Ellison], an LGC Fellow specializing in analytical statistics and <measurement uncertainty>.<Harmonised guidelines for the use of recovery information in analytical measurement by Michael Thompson and others>[Eurachem-hosted title page, printed Steven L R Ellison and affiliation 2.]{ref}<Stephen L. R. Ellison biography in the 2017 Eurachem workshop abstracts>[Printed p.94, named biography and explicit report-coauthorship link.]{ref}
The Eurachem biography also identifies him as a principal author of \i[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.<Stephen L. R. Ellison biography in the 2017 Eurachem workshop abstracts>[Printed p.94, scientific contributions.]{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 instead
$$
\sqrt{0.30^2+0.40^2+2(0.5)(0.30)(0.40)}\approx0.61\,\mathrm{mg}.
$$
The 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.
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