Hi Everyone,

I have a spatial dataset (US Counties with basic Census attributes and an
attribute denoting whether or not the county has a flood protection levee)
and I used t.test to compare the means between the groups.

All of my variables show clustering and neighborhood effects.  Is there a
t.test procedure that accounts for spatial correlation?  Is this even
necessary?

I've looked through Applied Spatial Data Analysis with R along with many of
the tutorials and notes available online and I have not found any mention of
such a procedure.  In Dalgaard (2008) I found the following statement about
the t.test: 'The t tests are fairly robust against departures from the
normal distribution' which seems to say that it is not necessary to account
for spatial effects.  But, I wanted to see what people on the list thought
about that?

Thanks,
Ezra

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