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Message-ID: <54612.98.122.165.51.1265230174.squirrel@webmail.ncsu.edu>
Date: 2010-02-03T20:49:34Z
From: Kristen M. Kostelnik
Subject: clumping vs. random
In-Reply-To: <25430_1265227616_o13K6mHF011015_1aef26221002031201t3c104a50iab6b7e7d4 41c09ff@mail.gmail.com>

Hello list,

It seems this should be quite a basic question, but I have no idea how to
approach it.  For 100s of sites, I have an environmental variable that has
occurences over a 20 year period.  I am looking for a way to create an
index between 0 and 1 that represents the degree of clumpiness vs.
randomness over time.  Where 0 is totally clumped and 1 is totally spaced
out evenly.

So for example:

Site     Year1   Year2  Year3   Year4......Year19   Year20    Total   Index
1         Yes     Yes    Yes     Yes        No        No      10       0
2         Yes     No     Yes     No        Yes        No      10       1

Yes and No can be converted to 1 and 0.  I am not sure what you call this
sort of index, technically, so I am not sure how to search for an
appropriate method.  I am, obviously, looking for a way to do this in R.

Thanks for any suggestions!
Kind Regards,
Kristen