Hydrology and Land Surface Studies
Nature's style: Naturally trendy
Article first published online: 8 DEC 2005
Copyright 2005 by the American Geophysical Union.
Geophysical Research Letters
Volume 32, Issue 23, December 2005
How to Cite
2005), Nature's style: Naturally trendy, Geophys. Res. Lett., 32, L23402, doi:10.1029/2005GL024476., and (
- Issue published online: 8 DEC 2005
- Article first published online: 8 DEC 2005
- Manuscript Accepted: 12 OCT 2005
- Manuscript Revised: 29 SEP 2005
- Manuscript Received: 29 AUG 2005
 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.