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FUSEK, M. MICHÁLEK, J. VÁVROVÁ, M.
Original Title
Evaluation of contamination data with non-detects using censored distributions
Type
journal article in Web of Science
Language
English
Original Abstract
When measuring concentration of chemical compounds, we often have to deal with a~situation when the resulting values are found below the limit of detection or limit of quantification of the determination method. In order to statistically evaluate such data, the method of maximum likelihood considering doubly left-censored samples is applied. As a model distribution of measured concentrations, Weibull distribution is considered. Moreover, considering the asymptotic properties of maximum likelihood estimates, concentrations of chemicals can be compared using Wald's test based on the expected Fisher information matrix. Here we show that the described statistical method allows for a better evaluation of the obtained experimental data than commonly used methods where all values below the detection limits are replaced by a~constant. These methods are used for an analysis of the worldwide commonly used synthetic musk compounds (nitro and polycyclic) which were extracted from the fish samples caught upstream (Group 1) and downstream (Group 2) from a high-capacity wastewater treatment plant.
Keywords
Doubly left-censored sample, maximum likelihood, musk compound, Wald's test, Weibull distribution
Authors
FUSEK, M.; MICHÁLEK, J.; VÁVROVÁ, M.
RIV year
2015
Released
3. 12. 2015
ISBN
1018-4619
Periodical
Fresenius Environmental Bulletin
Year of study
24
Number
11c
State
Federal Republic of Germany
Pages from
4165
Pages to
4172
Pages count
8
BibTex
@article{BUT115693, author="Michal {Fusek} and Jaroslav {Michálek} and Milada {Vávrová}", title="Evaluation of contamination data with non-detects using censored distributions", journal="Fresenius Environmental Bulletin", year="2015", volume="24", number="11c", pages="4165--4172", issn="1018-4619" }