Extension of Fong and Alvarez: when is a lower limit of detection low enough?

The work of Fong and Alvarez is easily extended for counting when paired counting is not employed. It remains true in the general case that the precision of a counting method can be no less than about 30% at the LLD and so it is desirable to have decision levels at least several times larger than the LLD so that measurements have sufficient precision to make valid decisions.