|
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 158411 bytes)
GEOPHYSICAL RESEARCH LETTERS,
VOL. 32,
L23402,
doi:10.1029/2005GL024476,
2005
Nature's style: Naturally trendy
Timothy A. Cohn
U.S. Geological Survey, Reston, Virginia, USA
Harry F. Lins
U.S. Geological Survey, Reston, Virginia, USA
Abstract
Hydroclimatological time series often exhibit trends. While trend magnitude can be determined with little ambiguity, the corresponding statistical significance, sometimes cited to bolster scientific and political argument, is less certain because significance depends critically on
the null hypothesis which in turn reflects subjective notions about what one expects to see. We consider statistical trend
tests of hydroclimatological data in the presence of long-term persistence (LTP). Monte Carlo experiments employing FARIMA
models indicate that trend tests which fail to consider LTP greatly overstate the statistical significance of observed trends
when LTP is present. A new test is presented that avoids this problem. From a practical standpoint, however, it may be preferable
to acknowledge that the concept of statistical significance is meaningless when discussing poorly understood systems.
Received 29
August
2005;
accepted 12
October
2005;
published 8
December
2005.
Index Terms: 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 1694 Global Change: Instruments and techniques; 1833 Hydrology: Hydroclimatology; 1872 Hydrology: Time series analysis (3270, 4277, 4475); 1894 Hydrology: Instruments and techniques: modeling.
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 158411 bytes)
Citation: Cohn, T. A., and H. F. Lins
(2005),
Nature's style: Naturally trendy,
Geophys. Res. Lett.,
32,
L23402,
doi:10.1029/2005GL024476.
This paper is not subject to U.S. copyright. Published in 2005 by the
American Geophysical Union.
|