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dc.contributor.authorDeVries, Todd Alan
dc.contributor.authorHamilton, Martin A.
dc.identifier.citationDeVries, T., M. Hamilton."Estimating the Antimicrobial Log Reduction: Part 2. Presence/Absence Assays," Quantitative Microbiology, 1:47-62 (1999).en_US
dc.description.abstractThis is part 2 of a pair of papers on antimicrobial assays conducted to estimate the log reduction (LR), in the density of viable microbes, attributable to the germicide. Two alternative de®nitions of LR were de®ned in part 1, one based on the mean of the log-transformed densities; the other is based on the logarithm of the mean of densities. In this paper, we evaluate statistical methods for estimating LR from an antimicrobial assay in which the responses are presence=absence observations at each dilution in a series of dilutions. We provide a model for the presence=absence data, and, for each de®nition of LR, we derive the maximum likelihood estimator (mle). Using computer simulation methods, we compare the mle to several alternative estimators, including an estimator based on averaging the log-transformed most probable number (mpn) values. Standard error formulas for the estimators are also derived and evaluated using computer simulations. This investigation results in the following recommendations. If the parameter of interest is based on the mean of log-transformed densities, then the results favor use of the log-transformed mpn method. If, however, the parameter of interest is based on the logarithm of the mean of densities, then the results show that the mle should be used.en_US
dc.titleEstimating the antimicrobial log reduction: part 2. presence/absence assaysen_US
mus.citation.journaltitleQuantitative Microbiologyen_US
mus.identifier.categoryEngineering & Computer Scienceen_US
mus.relation.collegeCollege of Engineeringen_US
mus.relation.departmentCenter for Biofilm Engineering.en_US
mus.relation.departmentChemical & Biological Engineering.en_US
mus.relation.departmentChemical Engineering.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.relation.researchgroupCenter for Biofilm Engineering.en_US

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