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Thu, 16 Apr 2015 09:00:25 -0400 |
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Hi,
Here in my small part of the state (~41.5 N x 81.3 W) the numbers of
American Golden Finches is average.
Keep in mind that populations have random variation, and this is normal.
It takes considerable analysis to determine if there is a special or
assignable cause to any change which goes far beyond anecdotal
observation. Regression based analysis (T tests and similar tools) usually
consider far too limited a data set and do not look at variation around the
mean in a way that determines if variation is normal and random or due to a
special (outside) cause.
This is not to say that anecdotal observation is not important. If
multiple observers across a wide area report similar conditions these can
be indicative of a wider and more significant phenomena.
Haans
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