[CivicAccess-discuss] postal code-->electoral district: a free + legal way

[Tracey P. Lauriault]

Been away for a couple of days!

These folks did some interesting work here with postal codes but I do not
know the level of accuracy - http://www.voteforenvironment.ca/

Jennifer, if you go through the archives of the civicaccess.ca list you will
find two or three threads that discuss this file and its accuracy & access
issues.

*Russel* over at *Copyright Canada* has developed a tool here -
http://www.digital-copyright.ca/edid/postal, and has an MP letter writing
tool created to request for access to this file that might be helpful for
the discussion thread you forwarded earlier.*Letter re-postal code file* *and
the tool he used to help you generate it are here* -
http://www.digital-copyright.ca/edid/letter5.

I also know that *Mike* over at *Open Concept *(
http://openconcept.ca/services) has done some work with the postal code file
and perhaps he can point us to some of the issues he encountered.

Daniel is correct, the issue here is accuracy, you want to make sure that
you continuously have the updated file and that you are working with polygon
to polygon to ensure you have the correct postal code in the correct
riding.  The other tools are not accompanied with metadata and therefore it
is uncertain if they did a quality check or what base data they used.  This
is a typical problem with may great hacks, no metadata for the user to
evaluate the tool, assess the algorithm nor trace the data source.

Cheers
Tracey

On Thu, Jan 29, 2009 at 12:02 PM, Joe Murray
<joe.murray at jmaconsulting.biz>wrote:

> The Elections Canada / StatsCan list for PC -> EDID is known to have
> significant data quality issues unrelated to a postal code geographically
> overlapping riding boundaries. There are up to 7 ridings for a single
> postal
> code in their data last I looked, with tens of thousands of postal codes
> having multiple entries if I recall correctly. The methodology they've used
> to create the table is the issue.
>
> > <jenniferlianne at yahoo.ca> wrote:
> > >
> > > Isn't that a problem with all postal code to electoral district
> > resolvers?
> > >
> > > Jennifer
> >
> > Well, something is definitely fubared with these lists, because they
> > don't all return the same results.
> >
> > Technically though, it should be an area overlap. For those postal
> > codes that overlap 2 or more EDIDs, all possibilities should be
> > returned in a query.
> >
> > Otherwise, we mislead a fraction of voters.
> >
> > d.
>
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-- 
Tracey P. Lauriault
613-234-2805
https://gcrc.carleton.ca/confluence/display/GCRCWEB/Lauriault
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