Steve Friedman <friedman.steve <at> gmail.com> writes:
>
> Hi everyone,
>
> I'm working with a modest sized spatial database consisting of 1513
records
> and 50 variables. Fourteen of these are dummy variables delineating
> regional planning councils. I'm trying to understand how to integrate
the
> dummy variables in the geographically weight regression model. I'm
reading
> Fotheringham et.al. and see reference to using dummy variables, but I
don't
> see an example ilustrating the procedure. I also don't see an example
in
> the spgwr.pdf files associated with the package.
>
> If anyone has experience with this I'd certainly like to hear from you.
As you may know, so-called GWR models are severely subject to collinearity
impacting local coefficients.
In R, dummy variables are operationalised as factors, split out into the
appropriate dummies within model functions from the formula argument. So just
put the categorical variable (factor) in the RHS of the formula, and it will
just happen. So gwr(y ~ regional_planning_councils + ..., ...) for gwr in the
spgwr package will just work for factor regional_planning_councils with 14
levels.
The R-sig-geo list is more focused on this kind of question.
Roger
>
> I'm using R-2.5.1 on a PC.
>
> Thanks in advance.
>
> Steve
>
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>
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