Measurement uncertainty in water microbiology may not estimate the laboratory's precision

It has been proposed that microbiology laboratories introduce a measurement uncertainty for organism counts. Suggested methods of achieving this involve studying replicate counts from subsamples. This will overwhelmingly estimate the natural variation in numbers of organisms present in different subsamples, and the different characteristics of strains of organisms within the species or group (e.g. the coliform bacteria) being counted. Thus any measure of the laboratory's competence, in terms of precision, will be masked. In chemistry there is likely to be much more complete homogeneity of an analyte in a test material and these replicate measures will illustrate whether the laboratory is competent in achieving accurate results.