Date: Mon, 26 Sep 2005 09:55:47 +1000
Reply-To: Frank Milthorpe <Frank.Milthorpe@dipnr.nsw.gov.au>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Frank Milthorpe <Frank.Milthorpe@dipnr.nsw.gov.au>
Subject: Re: 2nd Attempt: Grouping Zip Codes - Integer programing may be
the solution
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Hi
I am working though a backlog of email messages.
Can you provide some information on the number of zip codes in your
dataset? If this a smallish number, say 100 you can probably get close
to the minimum of sets "manually" by using a map and / or possibly a
Geographic Information System. If you start at the zip codes at the
extremities and group all regions within 10 minutes this will reduce the
size of the problem. You could keep working through the problem.
Automated solutions are much better, especially if you decide the
cut-off interval should be 15 minutes, rather than 10 minutes. To be
sure that you are using the minimum number of groups sounds like an
integer programming problem. I am sure that there are packages out
there. I suspect that the cost of them may be comparable to SPSS. This
is not an area that I have not been involved in since my undergraduate
days. Is there anyone on the list who is aware of IP packages?
Cheers
Frank
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Frank Milthorpe
Senior Manager, Transport Modelling
Transport and Population Data Centre
Department of Planning
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