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Inaccuracy of counts of organisms in water or other samples: effects of pre‐dilution
Author(s) -
Tillett Hilary E.,
Farrington C.P.
Publication year - 1991
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.1991.tb00599.x
Subject(s) - confidence interval , dilution , statistics , sampling (signal processing) , environmental science , mathematics , computer science , physics , filter (signal processing) , computer vision , thermodynamics
Samples, such as raw waters, which contain large numbers of organisms will need to be pre‐diluted before culture, in order to count or estimate the numbers present. This introduces a further approximation into the results obtained from routine sampling and laboratory procedures. Computers allow calculation of 95% confidence intervals (c.i.) for the estimated count in the pre‐dilution sample. Although such confidence intervals can be wide, the variation in the density of organisms in the water source will be as large and probably much larger than the confidence intervals suggest. Accordingly, it is not surprisng that series of results from routine samples are highly variable.