Hi Bhartendu,

I've compared the function bw.ggwr between the V1.2-1 and V1.2-3.  Actually, there are two places we'v changed:
1. the default kernel function is changed from "gaussian" to "bisquare"
2. the calculation of AICc according to Tomoki's amendation:
AICc<--2*llik + 2*tr.S*dp.n/(dp.n-tr.S-2) (calculation in V1.2-1)
 AICc<--2*llik + 2*tr.S + 2*tr.S*(tr.S+1)/(dp.n-tr.S-1) (calculation in V1.2-3)
where the new one is a generic form of AICc.
Sorry for missing the second piece of update.  Hope this clarifies your doubt. Both of them are resonable for bandwidth  selection, but we are using the new one in the latest version. Cheers.

Binbin


 
From: bhartendupandey
Date: 2014-07-17 22:53
To: r-sig-geo
Subject: Re: [R-sig-Geo] GWmodel package results
Dear Dr. Lu,
 
Thank you for your prompt reply.
 
I understand that these are two different versions with different default
kernel functions. But I noticed something strange here. Even when I specify
the kernel function in bw.ggwr() as "bisquare" and run the code in the two
versions, i.e., GWmodel_1.2-1 and GWmodel_1.2-3, I get different bandwidth
estimates. This further is yielding inconsistent parameter estimates from
the two versions of the package. This is, in fact, keeping me confounded of
the reliability of results from the two versions. Or if the differences here
is merely because I am doing something anomalous.
I ran the following codes in two different computers installed with
different versions of the GWmodel package, as stated above: 
 
rm(list=ls())
require(GWmodel)
data(LondonHP)
DM<-gw.dist(dp.locat=coordinates(londonhp))
bw.f2 <- bw.ggwr(BATH2~FLOORSZ,data=londonhp, dMat=DM,family
="binomial",adaptive=T, kernel='bisquare',approach='AIC')
res.binomial<-gwr.generalised(BATH2~FLOORSZ, bw=bw.f2,data=londonhp,
dMat=DM,
              family ="binomial",adaptive=T, kernel='bisquare')
 
rm(list=ls())
require(GWmodel)
data(LondonHP)
DM<-gw.dist(dp.locat=coordinates(londonhp))
bw.f2 <- bw.ggwr(BATH2~FLOORSZ,data=londonhp, dMat=DM,family
="binomial",adaptive=F, kernel='bisquare',approach='AIC')
res.binomial<-gwr.generalised(BATH2~FLOORSZ, bw=bw.f2,data=londonhp,
dMat=DM,
              family ="binomial",adaptive=F, kernel='bisquare')
 
 
When I run this code in computer 1, I get, 
 
1.  Adaptive bandwidth: 269 (number of nearest neighbors)
2.  Fixed bandwidth: 36091.69 
 
and when I run it in computer 2, I get 
 
1. Adaptive bandwidth: 273 (number of nearest neighbors)
2. Fixed bandwidth: 35582.65  
 
Computer 1:
 
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
 
locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    
 
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
 
other attached packages:
[1] GWmodel_1.2-3     robustbase_0.91-1 maptools_0.8-30   sp_1.0-15        
 
loaded via a namespace (and not attached):
[1] DEoptimR_1.0-1  foreign_0.8-61  grid_3.1.0      lattice_0.20-29
[5] tools_3.1.0    
 
 
Computer 2: 
 
> sessionInfo()
R version 3.0.0 (2013-04-03)
Platform: x86_64-w64-mingw32/x64 (64-bit)
 
locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    
 
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
 
other attached packages:
[1] GWmodel_1.2-1     robustbase_0.9-10 maptools_0.8-26   sp_1.0-11        
 
loaded via a namespace (and not attached):
[1] foreign_0.8-53  grid_3.0.0      lattice_0.20-15 tools_3.0.0   
 
 
I thank you for your help and time. 
 
Best regards,
Bhartendu Pandey
 
 
 
 
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