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Activity Number:
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321
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Type:
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Topic Contributed
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Date/Time:
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Tuesday, July 31, 2007 : 2:00 PM to 3:50 PM
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Sponsor:
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Section on Statistics and the Environment
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| Abstract - #309305 |
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Title:
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The Uncertain Hockey Stick: A Statistical Perspective on the Reconstruction of Past Temperatures
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Author(s):
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Douglas Nychka*+
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Companies:
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National Center for Atmospheric Research
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Address:
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Box 3000, Boulder, CO, 80307-3000,
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Keywords:
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Hockey Stick ; uncertainty ; ensembles ; NH temperature
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Abstract:
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A reconstruction of past temperatures based on proxies is inherently a statistical process and a deliberate statistical model for the reconstruction can also provide companion measures of uncertainty. we suggest a framework where the reconstruction is expressed as a conditional distribution of the temperatures given the proxies. Random draws from this distribution provide an ensemble of reconstructions where the spread among ensemble members is a valid statistical measure of uncertainty. This approach is illustrated for Northern Hemisphere temperatures and the multi-proxy data used by Mann, Bradley and Hughes (1999). Here we explore the scope of the statistical assumptions needed to carry through a rigorous analysis and use Monte Carlo sampling to determine the uncertainty in maxima or other complicated statistics in the reconstructed series.
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