[Openspace] Multiple observations per location in GeoDa

[Josh Woodard]

Graeme,



You may find the following files useful.  I had experimented with something 
similar in the past so I had this laying around.  In the file 
"CreateMultiLocWeights" you will find VBA code to do what you describe (open 
the VBA editor to view the code).  It's not pretty, but should provide a one 
time solution.  Basically, what it does is creates GAL weights for 
individual observations when only the area the observations are in are 
known.  Each observation in each area will be a neighbor of each observation 
in that area, and also all observations in neighboring areas will become 
neighbors as well.  You need the shapefile for the areas or the GAL file for 
the area weights.  Obviously you won't get a shapefile for the individual 
observations, but you can do reg's with just the dbf and weights in GeoDa. 
You can create it using this code in Excel '07 as long as you don't have 
more than about 600,000 or so observations (or about 32,000 if you don't 
have Excel '07).



I am not sure how "appropriate" this is statistically, so I would not be the 
one to consult on that, but this should help you in creating such a weights 
file which can be used in GeoDa.  I would be interested to hear anyone else's 
thoughts on such a design though as I ran across a similar problem.  I was 
able to implement it fine, but wasn't quite sure if this was a viable 
approach.



There are some short instructions and an example to show you how to convert 
the files back and forth.  Please let me know if you have any questions or 
run into any problems. Let me know if you have GWT weights or need to GWT 
weights...I have some code for that too.



Josh Woodard




Use the following links to access the corresponding files:

/jdwoodar/Spatial/MultiWeightsExample.zip:
https://netfiles.uiuc.edu/xythoswfs/webui/_xy-25926587_2-t_Er3YgGgx



-----------------------------------------------------------------------------
Joshua D. Woodard
Ph.D. Candidate
Office for Futures and Options Research (OFOR)
Farmdoc-Finance, Insurance, and Risk Management Group
Department of Agricultural and Consumer Economics
University of Illinois at Urbana-Champaign




----- Original Message ----- 
From: "Graeme Byrne" <G.Byrne at latrobe.edu.au>
To: <openspace at sal.uiuc.edu>
Sent: Saturday, November 10, 2007 9:03 PM
Subject: [Openspace] Multiple observations per location in GeoDa


Hi all, I have spatial regression problems where there are multiple 
observations per locations. One particular model has cases for males and 
females from the same place and I want to estimate the effect of gender (via 
a dummy variable) as well as the effect of some gender specific covariates. 
I can create a shape file from MapInfo but GeoDa requires a unique location 
for each case so at the moment I am fitting separate models for males and 
females which works but reduces the power of statistical tests. Ideally I 
would like to include gender and possibly other factors (e.g. Age) in a 
single SAR or SE model. Are there R routines available or can GeoDa be 
coerced into doing this

Graeme