DENNIS R. HELSEL (USGS). John Wiley and Sons, New York. 2004. Hardcover, 268 pp. US $94.95. ISBN 0–471–67173–8.

Helsel's Book: A Clever Thing About Supposedly Nothing

We have all seen them in textbooks, papers, or our own research datasets—the dreaded “less than” data, those environmental (most often chemical analysis) data that are “less than” some detection or reporting limit or some other small limit. In the interpretation and particularly in the statistical analysis of environmental data, the “less than” data or “nondetects” are but a nuisance to the practitioner: our beloved software programs apparently have no use (at least that...

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