In contrast, Figure and Equation show that a recovery error amplification less than 1 can occur much more easily, namely when a species has a low tailings grade and a large difference between the feed and tailings grade. This situation occurs frequently when a lowgrade feed is being treated to obtain a high-grade product at low yield to product. So, it is possible for the value of the calculated yield to have considerable uncertainty, and yet still be confident about the calculated recovery (e.g. if a species has zero tailings assay but a finite assay in the feed stream, then we can be confident the recovery of that species is close to 100 %, even though we may not know the overall yield very accurately). Conversely, Equation shows that the recovery error amplification will tend to be large when a species has a high grade in the tailings and a similar concentration in both the feed and tailings stream. In practice this means that the recovery to product of a dominant gangue species will often be very uncertain.