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st: SPATGSA


From   Ivan Png <iplpng@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: SPATGSA
Date   Sun, 31 Oct 2010 11:34:07 +0800

Greetings!

I'm trying to estimate spatial correlation.  I gave the following commands:

         use moran_working.dta , clear
         spatwmat , name(wts) xcoord(longitude) ycoord(latitude) band(0, 1000)
         spatgsa rd_int , weights(wts) moran

The result was nothing:
The following matrix has been created:

1. Inverse distance weights matrix wts
   Dimension: 511x511
   Distance band: 0 < d <= 1000
   Friction parameter: 1
   Minimum distance: 0.0
   1st quartile distance: 0.5
   Median distance: 2.8
   3rd quartile distance: 5.4
   Maximum distance: 10.5
   Largest minimum distance: 2.59
   Smallest maximum distance: 5.79



.          spatgsa rd_int , weights(wts) moran


Measures of global spatial autocorrelation


Weights matrix
--------------------------------------------------------------
Name: wts
Type: Distance-based (inverse distance)
Distance band: 0.0 < d <= 1000.0
Row-standardized: No
--------------------------------------------------------------

Moran's I
--------------------------------------------------------------
          Variables |    I      E(I)   sd(I)     z    p-value*
--------------------+-----------------------------------------
             rd_int |      .  -0.002   0.003       .       .
--------------------------------------------------------------
*1-tail test

======================


I also tried
         spatwmat , name(wts) xcoord(longitude) ycoord(latitude) band(0, 1000)
         spatgsa rd_int , weights(wts) geary

and also got nothing:

The following matrix has been created:

1. Inverse distance weights matrix wts
   Dimension: 511x511
   Distance band: 0 < d <= 1000
   Friction parameter: 1
   Minimum distance: 0.0
   1st quartile distance: 0.5
   Median distance: 2.8
   3rd quartile distance: 5.4
   Maximum distance: 10.5
   Largest minimum distance: 2.59
   Smallest maximum distance: 5.79



.          spatgsa rd_int , weights(wts) geary


Measures of global spatial autocorrelation


Weights matrix
--------------------------------------------------------------
Name: wts
Type: Distance-based (inverse distance)
Distance band: 0.0 < d <= 1000.0
Row-standardized: No
--------------------------------------------------------------

Geary's c
--------------------------------------------------------------
          Variables |    c      E(c)   sd(c)     z    p-value*
--------------------+-----------------------------------------
             rd_int |      .   1.000   0.187       .       .
--------------------------------------------------------------
*1-tail test

=====================


I've had the same problem with hundreds of similar data-sets.
Grateful for your help.  In case it would help in debugging, I've
uploaded a sample data-set here:

http://www.comp.nus.edu.sg/~ipng/research/moran_working.dta

Many thanks
Ivan Png



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