A grab sampling strategy could consist of 1 to n grab samples. However, there were 1244 and 1258 possible single grab samples between 9 a.m. and 5 p.m. on working days in respectively dataset 1 and dataset 2. Taking a lot of grab samples is not very practical. In order to mimic a practical grab sampling strategy, 1 to 300 random grab samples were taken from the 1244 or 1258 possible grab samples. For each n, the n grab samples were averaged to obtain an estimated ER and then converted to kg year−1 (animal place)−1. This resulted in 300 estimates, one for each value of n.