The centroid of population is a weigthed average.  Here's one way to do it
using SQL select.

Fields: WtAvg(CentroidX(obj),YourPopulationField),
WtAvg(CentroidY(obj),YourPopulationField)
Tables: YourTable
Where: Rowid < 1000000000


The condition is a dumy one. So ensure that all the objects will be included
in the calculation,
use a rowid number higher than the number of objects of your table.

Save the temporary Queryn as a base table. Open it, and use Table-Create
Point to create
the object representing the population centroid.

Good luck,





> -----Message d'origine-----
> De:   David Saladino [SMTP:[EMAIL PROTECTED]]
> Date: Wednesday, July 07, 1999 10:06 AM
> :    '[EMAIL PROTECTED]'
> Objet:        MI Regional Centroids
> 
> Hello all,
> 
> I'm trying to determine the centroid of population of our 2-County region.
> Our population data is broken down into Traffic Analysis Zones (TAZ) of
> which there are roughly 500 in the region.  Is there any way to plot this
> centroid of population?  My goal is to track the movement of this centroid
> over the years.
> 
> Any help would be greatly appreciated.
> 
> ______________________________
> 
> David Saladino
> Wilmington Area Planning Council
> 850 Library Avenue, Suite 100
> Newark, DE 19711
> Phone: (302) 737-6205 x13
> Fax:     (302) 737-9584
> E-mail:  [EMAIL PROTECTED]
> Web:    http://www.wilmapco.org
> 
> 
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