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Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984

Water-Resources Investigations Report 87-4050
By: , , and 
https://doi.org/10.3133/wri874050

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Abstract

The U.S. Geological Survey operated a blind audit sample program during 1974 to test the effects of the sample handling and shipping procedures used by the National Atmospheric Deposition Program and National Trends Network on the quality of wet deposition data produced by the combined networks. Blind audit samples, which were dilutions of standard reference water samples, were submitted by network site operators to the central analytical laboratory disguised as actual wet deposition samples. Results from the analyses of blind audit samples were used to calculate estimates of analyte bias associated with all network wet deposition samples analyzed in 1984 and to estimate analyte precision. Concentration differences between double blind samples that were submitted to the central analytical laboratory and separate analyses of aliquots of those blind audit samples that had not undergone network sample handling and shipping were used to calculate analyte masses that apparently were added to each blind audit sample by routine network handling and shipping procedures. These calculated masses indicated statistically significant biases for magnesium, sodium , potassium, chloride, and sulfate. Median calculated masses were 41.4 micrograms (ug) for calcium, 14.9 ug for magnesium, 23.3 ug for sodium, 0.7 ug for potassium, 16.5 ug for chloride and 55.3 ug for sulfate. Analyte precision was estimated using two different sets of replicate measures performed by the central analytical laboratory. Estimated standard deviations were similar to those previously reported. (Author 's abstract)

Suggested Citation

Brooks, M.H., Schroder, L., and Willoughby, T.C., 1987, Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984: U.S. Geological Survey Water-Resources Investigations Report 87-4050, iv, 19 p. :ill. ;28 cm., https://doi.org/10.3133/wri874050.

Publication type Report
Publication Subtype USGS Numbered Series
Title Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984
Series title Water-Resources Investigations Report
Series number 87-4050
DOI 10.3133/wri874050
Year Published 1987
Language ENGLISH
Publisher U.S. Geological Survey,
Description iv, 19 p. :ill. ;28 cm.
Additional publication details