You haven't given quite enough information to be sure, but I would guess that this is not really a problem, but rather the interesting proporty of GLMs fitted with a canonical link described in e.g. section 2.1.8 of Wood (2006) Generalized additive models: and introduction with R, or at the beginning of the GLM chapter in Venables and Ripley MASS.
On Friday 21 August 2009 22:03, Lucía Rueda wrote: > Hi, > > I am comparing the observed and fitted values of my GAM model, which > includes the explanatory variables: longitude, depth, ssh, year and month. > When I compare observed and fitted values for longitude, depth and ssh it > works. But when I try to do it for month and year (which are as factors in > the GAM model) it doesn't work. My observed and fitted values are exactly > the same.. How is that possible?� Thanks > > > Obs_factor1<-aggregate(x=albdata$turtles,by=list(albdata$Year),FUN=mean) > > names(Obs_factor1)=c("Bin","Observed") > > Obs_factor1 > > ��� Bin��� Observed > 1� 1997 0.017094017 > 2� 1998 0.010652463 > 3� 1999 0.023000000 > 4� 2000 0.017167382 > 5� 2001 0.030465950 > 6� 2002 0.007446809 > 7� 2003 0.010568032 > 8� 2004 0.011450382 > 9� 2005 0.016270338 > 10 2006 0.017006803 > 11 2007 0.030969031 > 12 2008 0.066455696 > > > Fit_factor1<-aggregate(x=predict(gam.def.lon,type="response"),by=list(alb > >data$Year),FUN=mean) names(Fit_factor1)=c("Bin","Fitted") > > Fit_factor1 > > ��� Bin����� Fitted > 1� 1997 0.017094017 > 2� 1998 0.010652463 > 3� 1999 0.023000000 > 4� 2000 0.017167382 > 5� 2001 0.030465950 > 6� 2002 0.007446809 > 7� 2003 0.010568032 > 8� 2004 0.011450382 > 9� 2005 0.016270338 > 10 2006 0.017006803 > 11 2007 0.030969031 > 12 2008 0.066455696 > > > > > > > [[alternative HTML version deleted]] -- > Simon Wood, Mathematical Sciences, University of Bath, Bath, BA2 7AY UK > +44 1225 386603 www.maths.bath.ac.uk/~sw283
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