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RE: st: spmat idistance error
Ajita Atreya <email@example.com>
RE: st: spmat idistance error
Mon, 30 Jan 2012 19:27:34 +0000
Sorry about the confusion in my code. I actually have a name for spmat object which I missed to type.
My code is:
spmat idistance idoug longitude latitude, id(id) dfunction(dhaversine) vtruncate(1/.2) normalize(minmax) banded
****idoug is the name of my spmat object which I want to use in spreg command
The command I used for running spatial regression is
spreg g2sls lnprice ........, id(id) dlmat(idoug) elmat(idoug)
My question here is can stata form a banded inverse-distance matrix (24,000 obs) that I can use in my Spreg command. I have read the spmat working paper and did exactly the same thing to band a matrix that is described but unfortunately it did not work.However, the same banding process works well with the contiguity matrix.Please suggest alternative if any
> From: firstname.lastname@example.org
> To: email@example.com
> Subject: st: spmat idistance error
> Date: Mon, 30 Jan 2012 09:42:25 -0600
> Ajita Atreya <firstname.lastname@example.org> is trying to create a banded
> spatial-weighting matrix using the user-written -spmat- command but -spmat-
> > I have 24,000 observations on property prices. I am trying to create an
> > inverse distance matrix with truncation (200m) to use in spreg command.
> > I used the following code to create inverse distance matrix:
> > spmat idistance longitude latitude, id(id) dfunction(dhaversine)
> > vtruncate(1/.2) normalize(minmax) banded
> > The matrix was created once but when I re did it I started getting the error
> > as: Object not created-bands must be<=5516
> > The model I am using is :
> > spreg g2sls lnprice ........, id(id) dlmat(matrixname) elmat(matrixname)
> We would need to see all the syntax that Ajita typed to diagnose the problem.
> Meanwhile, I can offer some general thoughts. Ajita typed
> . spmat idistance longitude latitude, id(id) ...
> This statement should have created an spmat object named "longitude"; my guess
> is that Ajita meant to type something similar to
> . spmat idistance myobj longitude latitude, id(id) ...
> and -spmat- would have created an spmat object named "myobj".
> Whatever the case, the syntax for -spreg- would not work as in
> . spreg gs2sls ..., id(id) dlmat(matrixname) elmat(matrixname)
> options dlmat() and elmat() expect the name of an spmat object and from the
> code Ajita showed us, there is no spmat object named "matrixname".
> Re: banded matrices, Ajita should read section 5 of the spmat working paper,
> available at http://econweb.umd.edu/~prucha/Papers/WP_spmat_2011.pdf, too see
> whether the sorting trick described therein helps with banding the matrix.
> Finally, if Ajita has not done so, Ajita should also update -spmat- and
> -spreg- (and -spivreg-) to the latest version by typing
> . ssc install sppack, replace
> The updated code is slightly more memory efficient than the old version.
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