Spatial Regression with two Weights matrix (SAR)
On Fri, 25 Jul 2014, Linus Holtermann wrote:
Hello, is there a R function that could estimate the following spatial regression: y = rho_1*W1*y + rho_2*W2*y + XB + e W1 and W2 are not identical, of course.
No, not least because the mutual constraints on \rho_* are unknown. Too
little is known about (I - (\sum{i=1}{k}\rho_i W_i)) in the literature as
far as I am aware. It may seem attractive to see W_i as bands of
increasing distances, or graph steps, but these models actually work
through (I - \rho W)^{-1}, which includes all higher order
relationships implicitly. The same lack of knowledge about constraints
applies to the SEM error case:
y = X\beta + u, u = \sum{i=1}{k}(\rho_i W_i u) + e
but this is more like the case of a collection of variogram models.
In the SAR (lag), you also face the problem of finding the impacts, as the
\beta values should not be interpreted directly, as the reduced form is:
y = (I - (\sum{i=1}{k}\rho_i W_i))^{-1} (X\beta + e)
and the \rho's and \beta interact.
Contributions welcome,
Roger
Bests, Linus Holtermann Hamburgisches WeltWirtschaftsInstitut gemeinn?tzige GmbH (HWWI) Heimhuder Stra?e 71 20148 Hamburg Tel +49-(0)40-340576-336 Fax+49-(0)40-340576-776 Internet: www.hwwi.org Email: holtermann at hwwi.org AmtsgerichtHamburg HRB 94303 Gesch?ftsf?hrer: Prof. Dr. Thomas Straubhaar, Gunnar Geyer Umsatzsteuer-ID: DE 241849425
_______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
Roger Bivand Department of Economics, Norwegian School of Economics, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 91 00 e-mail: Roger.Bivand at nhh.no