ABSTRACT
The statistical analysis of microbial abundance determined by epifluorescence microscopy may appear to be more problematic than other measurements of microbial assemblages because there are several levels at which subsamples can be taken. An investigator could calculate an optimal sampling strategy for his or her specific problem by going through the equations. This chapter provides the following sampling strategy, based on the cost and error analysis of David L. Kirchman et al.: number of preserved subsamples: 2, number of filters per subsample: 1, and number of microscopic fields per filter: >7, probably 10. Several investigators base their counting strategies on the number of microorganisms per microscopic field, e.g., they continue until 300 cells are counted, and a graph is used to calculate the error, which is based solely on the number of cells per field.
