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Improving the interpretation of ‘less than’ values in environmental monitoring
Author(s) -
Gardner Mike
Publication year - 2012
Publication title -
water and environment journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 37
eISSN - 1747-6593
pISSN - 1747-6585
DOI - 10.1111/j.1747-6593.2011.00287.x
Subject(s) - interpretation (philosophy) , simple (philosophy) , principal (computer security) , computer science , risk analysis (engineering) , management science , subject (documents) , key (lock) , data science , engineering , epistemology , business , computer security , philosophy , programming language , library science
This paper reviews the approaches used to deal with the interpretation of measurements reported as ‘less than’ a stated reporting limit. The principal current methodologies are examined and their shortcomings discussed. Recent key papers on the subject are summarised. It is concluded that lack of easy‐to‐use alternative methods have led to the continued use of substitution methods that are acknowledged to be biased. With the aim of promoting a more technically sound approach to dealing with ‘less than’ data, a supplementary spreadsheet tool is supplied to provide the reader with ready introductory access to a simple way to apply maximum likelihood methods. Recommendations and simple guidelines for better practice are provided.