[Openspace] Univariate Moran
Marie-Helene.Vandersmissen at ggr.ulaval.ca
Mon Jun 12 09:01:38 CDT 2006
I used to work with MapStat implemented by Theriault (1998) in MapInfo to
calculate Moran's I . The approach of Theriault is similar to that Zhang
and Griffith (1997).
Since a few months, I work with GeoDa (I find it very usefull and extremely
well documented. Congratulations!). When I compare the Moran's I from
MapStat with the Moran's I from GeoDa, there's always a little difference.
Bailey & Gatrell (1995, p. 270) mention of an adjustment of Moran's I by
its theoretical bound. I did some tests with a small sample and I
performed the calculations by hand. The Moran's I performed by GeoDa
corresponds exactly to the one I got with the equation from Bailey &
Gatrell while the Moran's I performed by MapStat corresponds to the one I
got with the classical equation (without the adjustment for the range [-1.1]).
For example, the Moran's I performed by GeoDa equals -0,2979 while the
Moran's I performed by MapStat equals -0,2557. Does it mean that the result
of the ratio -0,2557/-0,2979 = -0,85 is similar to the usual non-spatial
Please, could you confirm that result and indicate if it is mentionned in
one of your publications? (I just want to well understand the difference
and to well explain that to my students).
With many thanks!
Departement de geographie et
Centre d'aménagement et de développement (CRAD)
Bureau 6257, Pavillon Charles-De-Koninck
Faculté de foresterie et de geomatique
Tél.: (418) 656-2131 poste 3056
Fax.: (418) 656-3960
Site du Departement: http://www.ggr.ulaval.ca
Site du CRAD: http://www.crad.ulaval.ca
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