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Is GWR in ggwr function with poisson distribiution the same as Geographically Weighted Poisson Regression (GWPR) disused by Nakaya 2005
2 messages · Roosbeh Nowrouzian, Roger Bivand
On Fri, 28 Dec 2012, Roosbeh Nowrouzian wrote:
Dear list members: I am wondering if Geographically weighted Regression(GWR) applied in Generalized Linear Models(GLM) framework with defined family="poisson" in ggwr.sel and ggwr functions is the same as Geographically Weighted Poisson Regression (GWPR) disused by Nakaya et al. 2005 for disease association mapping.
Since GWR3 and GWR4 are closed-source implementations, nobody knows whether they implement Nakaya et al. 2005 either. If you read the code of ggwr(), you'll see that it uses GW on glm() in a way that is probably not dissimilar to that proposed. But you'd need to check carefully on a test data set to see whether the local coefficients agree - probably glm() is a more robust GLM than that in GWR, certainly the OLS in GWR used to be based on very old matrix inversion code, something nobody serious does nowadays, because it is not numerically stable. You should also be concerned about overdispersion. Try rather GLMM or GAMM unless you have an unmeasurable non-stationarity - if it is measurable, re-specify the model to include it and forget GWR. Roger
Thanks Roosbeh Nowrouzian PhD Student University of Florida Department of Civil and Coastal Engineering
Roger Bivand Department of Economics, NHH Norwegian School of Economics, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: Roger.Bivand at nhh.no