We believe these very simple to use expressions are a practical outcome of this paper that will prove useful for metallurgists in providing an estimate of the uncertainty of yield and recovery values calculated when Equations 1 and 2 are applied to the assays of a single species. The calculated error amplifications will, of course, only be approximate, not only because the equations themselves are approximations (see Section 2.1.1) but also because one is forced to use the measured Gi,F and Gi,T values which themselves have errors, rather than the unknown true assay values. However, where this error amplification factor is large, say order of 10 or more, then it should give one cause to question how reliable the calculated yield or recovery value is.