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## AI-GEOSTATS: Significant Moran's I?

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• To measure auto-coorelation Moran s I is compared to the expected I that would be generated from a random distribution. My question is if the observed
Message 1 of 2 , Jul 10, 2003
To measure auto-coorelation Moran's I is compared to the expected "I" that
would be generated from a random distribution. My question is if the observed
Moran's I is more than one standard deviation higher than expected "I" could
that be considered significant auto-correlation?

Thanks
Russell Barbour Ph.D.
Research Associate in Applied Mathematics
Vector Ecology Laboratory
Yale School of Medicine
60 College St. Rm 600
New Haven CT. 06520
TEL: 203 785 3223
FAX 203 785 3604
email: russell.barbour@...

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• ... I guess that will depend on your specific application. If you permute your observed values about your spatial units, you can work out how far out in one of
Message 2 of 2 , Jul 24, 2003
On Thu, 10 Jul 2003, Russell Barbour wrote:

> To measure auto-coorelation Moran's I is compared to the expected "I" that
> would be generated from a random distribution. My question is if the observed
> Moran's I is more than one standard deviation higher than expected "I" could
> that be considered significant auto-correlation?

I guess that will depend on your specific application. If you permute your
observed values about your spatial units, you can work out how far out in
one of the tails your observed statistic falls. Where you want to set your
bound for a significant statistic is then a matter for your judgement,
although +1SD sounds permissive. Recall that Moran's I can also detect
non-stationarity, so is a general test for spatial mis-specification
(Fingleton, 1999, Journal of Regional Science).

Roger Bivand

>
> Thanks
> Russell Barbour Ph.D.
> Research Associate in Applied Mathematics
> Vector Ecology Laboratory
> Yale School of Medicine
> 60 College St. Rm 600
> New Haven CT. 06520
> TEL: 203 785 3223
> FAX 203 785 3604
> email: russell.barbour@...
>

Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand@...

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