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Main Title Testing for Trends When There Are Changes in Methods.
Author Newell, A. D. ; Blick, D. J. ; Hjort, R. C. ;
CORP Author ManTech Environmental Technology, Inc., Corvallis, OR.;Corvallis Environmental Research Lab., OR.
Publisher c1993
Year Published 1993
Report Number EPA/600/J-93/405;
Stock Number PB93-236420
Additional Subjects Water quality data ; Water pollution sampling ; Data collection ; Standards ; Environmental monitoring ; Trends ; Concentration(Composition) ; Calibrating ; Revisions ; Mathematical models ; Surveys ; Graphs(Charts) ; Statistical analysis ; Long term effects ; Reprints ; Kendall tau test
Library Call Number Additional Info Location Last
NTIS  PB93-236420 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 14p
Abstract Data from monitoring projects often include sampling or analytical changes that preclude trend analysis on the entire period of record. A modification of the nonparametric Kendall's test for monotonic trends, which accounts for such changes in the period of record, is described here. This approach blocks the data so that only data collected or analyzed under similar circumstances are compared. Alternatively, when appropriate data exist, data collected using the old method may be calibrated to values expected from the new method. Traditional trend tests may then be applied to resulting data sets. Results from simulations assessing both the power of the blocked test and the standard test performed on calibrated data are presented. The power of the blocked test exceeded the power of the calibration approach only when the calibration error was extremely large. Both the blocking and calibration approaches were applied to and compared for chemical data from Vermont lakes. (Copyright (c) 1993 Kluwer Academic Publishers.)
Supplementary Notes Pub. in Water, Air, and Soil Pollution, v67 p457-468 1993. See also PB93-236461 and PB88-215009. Sponsored by Corvallis Environmental Research Lab., OR.
NTIS Title Notes Journal article.
Title Annotations Reprint: Testing for Trends When There Are Changes in Methods.
Category Codes 68D; 48G
NTIS Prices PC A03/MF A01
Primary Description 600/02
Document Type NT
Cataloging Source NTIS/MT
Control Number 330925815
Origin NTIS
Type CAT