On Mon, 21 Jan 2002, Irene Schmidtmann wrote:
Hi,
Actually the exact distribution of Moran's I has been derived by
M. Teifesdorf, look at Environment and planning A 27:pp 285-999. It has
long been known that the normal approximation has strong assumptions
associated with it that often do not hold, becuase conditonal on the
weight matrix the distribution can be highly skewed.
Nicholas
>
> "Empirical Studies of Cluster Detection - Different Cluster Tests in
> Application to German Cancer Maps" in Disease Mapping and Risk Assessment for
> Public Health, eds. A. B. Lawson et al, 1999 John Wiley
>
> It seems that the distribution of Moran's I can be approximated reasonably well
> by a randomization approach even if the population figures differ in the
> regions. Oden (Adjusting Moran's I for population density, Statistics in
> Medicine 14, 17-26, 1996) has taken into account unequal population and
> modified the Moran statistic accordingly. (There has been debate whether
> Oden's normal approximation is correct, a limiting chi-square distribution may
> be more appropriate.)
>
> Yours sincerely
> Irene Schmidtmann
>
CH3
|
N Nicholas Lewin-Koh
/ \ Dept of Statistics
N----C C==O Program in Ecology and Evolutionary Biology
|| || | Iowa State University
|| || | Ames, IA 50011
CH C N--CH3 http://www.public.iastate.edu/~nlewin
\ / \ / [EMAIL PROTECTED]
N C
| || Currently
CH3 O Graphics Lab
School of Computing
National University of Singapore
The Real Part of Coffee [EMAIL PROTECTED]
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