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RECORD NUMBER: 735 OF 3040

OLS Field Name OLS Field Data
Main Title Designs for Assessment of Measurement Uncertainty: Experience in the Eastern Lake Survey.
Author Liggett, W. S. ;
CORP Author National Bureau of Standards (NEL), Gaithersburg, MD. Statistical Engineering Div.;Corvallis Environmental Research Lab., OR.
Publisher 1986
Year Published 1986
Stock Number PB89-173827
Additional Subjects Lakes ; Error analysis ; Environmental surveys ; Quality assurance ; Statistical analysis ; Assessments ; Probability theory ; Chromatographic analysis ; Inorganic nitrates ; Sulfates ; Performance evaluation ; United States ; Water pollution sampling
Holdings
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NTIS  PB89-173827 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 08/24/1989
Collation 15p
Abstract
As is typical of environmental studies, the Eastern Lake Survey generated data that reflect both properties of the environment and properties of the sampling and measurement procedures. Thus, environmental conclusions cannot be drawn from these data without assessment of the sampling and measurement error. The paper shows how the properties of ion chromatography affect the nitrate and sulfate measurements in the survey. The investigation, which is based on measurements of routine-duplicate samples, field blanks, and field audit samples, is interesting because of its complexity. The measurement error has a within-day component and a day-to-day component. The variance of the within-day component increases linearly with concentration except near zero where the algorithm used to interpret the chromatographs seems to behave poorly. The day-to-day component depends on the calibration procedure. As an example, this investigation illustrates the strengths and weaknesses of some common designs for uncertainty assessment.