Peculiar behaviour while conducting a location-allocation exercise

Discussion created by MarkShymanski on Jan 24, 2012
Latest reply on Jan 30, 2012 by MarkShymanski
This exercise is the precursor to a much larger project but I thought I'd start with a more manageable dataset and build from their.

I have a roughly 16 mile square with potentially 900 facilities and 990 demand points.  I am using the location-allocation tool in NA with Problem Type: Maximize Coverage; Facilities to Choose: 18, Impedance Cutoff: 1800, Impedence Transformation: Power and Impedance Power: 1.  The result I am getting is fairly sensible except for the unexpected clustering of two or three 'Chosen' facilities within each other's catchment.  I am also getting demand counts with a huge range (from 8 to 97 in the case of 20 chosen facilities and 8 to 156 in my 18 facility option.  I've had the data set tried on a different computer and it works as expected but when I do it on my machine (running XP proff. ArcGIS10 svpk 2) I get this weird behaviour.

Has anybody else had this experience?  Any suggestions as to what I should do totroubleshoot/fix it?  Any advice greatly appreciated!