| Abstract: | This paper extends the work of Gilliom and Helsel on procedures for estimating descriptive statistics of water quality data than contain "less than‘ observations. Previously, procedures were evaluated when only one detection limit was present. Here the performance of estimators for data that have multiple detection limits is investigated. Probability plotting and maximum likelihood methods perform substantially better than simple substitution procedures now commonly in use. Therefore simple substitution procedures eg substitution of the detection limit should be avoided. Probability plotting methods are more robust than maximum likelihood methods to misspecification of the parent distribution and their use should be encouraged in the typical situation where the parent distribution is unknown. When utilized correctly, less than values frequently contain nearly as much information for estimating population moments and quantiles as would the same observations had the detection limit been below them. -Authors |
| Genre: | Article |
| ProdID: | 70014353 |
| Citation Author: | Helsel, D. R.; Cohn, T. A. |
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| Citation End Page: | 2004 |
| Citation Issue: | 12 |
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| Citation Language: | English |
| Citation Larger Work Title: | Water Resources Research |
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| Citation Number Of Pages: | 8 |
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| Citation Search Results Text: | Estimation of descriptive statistics for multiply censored water quality data; 1988; Article; Journal; Water Resources Research; Helsel, D. R.; Cohn, T. A. |
| Citation Start Page: | 1997 |
| Citation Volume: | 24 |
| Citation Year: | 1988 |
| Type: | citation/reference |
| Text: | Estimation of descriptive statistics for multiply censored water quality data; 1988; Article; Journal; Water Resources Research; Helsel, D. R.; Cohn, T. A. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1988 00:00 -0600 |
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