Hi all,
Many of you have a magic number, 3.3219, as part of your formula for the
Shannon index from Doc Donnelly's NR 1. That number converts the Shannon
index calculated using base 10 logarithms to the value you would get if
you used base 2 logarithms. Since Shannon was a computer scientist, he
was thinking about the information contained in a block of binary code,
i.e., ones and zeroes. That is why he derived the equation using base 2.
Excel can compute base 2 logarithms. The formula is
=LOG(__,2)
You can use natural logarithms (as in your textbook), base 10, or base 2
 just tell your readers (me and Bethany in this case) which one you used.
Kristian

Kristian Omland
Postdoctoral Research Associate
Vermont Cooperative Fish & Wildlife Research Unit
Rubenstein School of Environment & Natural Resources
University of Vermont
Burlington VT 05405
voice: (802)6562496 fax: (802)6568683
web page: http://www.uvm.edu/~komland
