in a way that should have yielded only a 5 percent chance of incorrectly concluding that there was a trend. The approach that accounts for spatial correlation, concludes that there is a trend 5 percent of the time, as expected. Overall, this example illustrates that statistical approaches that ignore spatial and/or temporal correlation inherent in environmental data carry with them an increased risk of erroneously concluding that significant relationships exist between physical phenomena (snow depth and elevation, in this case), and, more generally, yield biased estimates due to their assumption of independent observations.



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