[R] LOCFIT help

[Takatsugu Kobayashi]

Hi,

I have started to learn local regression models so as to identify
statistically significant peaks in urban areas, such as population
densities and congestion. I successfully ran /locfit/ and got several
information on the fit. Now I got stuck. This is a very silly question,
but isn't the first derivative of the fitted curve zero or close to
zero? I got some very high numbers on that.

The commands I put are:

x<-Longitude
y<-Latitude
model.local<-locfit(log(POPDENSITY)~lp(x,y, nn=0.55))

span was determined by spgwr adaptive bandwidth.

Any help appreciated.

Thank you very much.

Taka

PhD student
Indiana University, Geography