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Probelms on using gam(mgcv)
2 messages · zhijie zhang, Simon Wood
A smooth of `disbinary' doesn't really make sense. It should enter the model parametrically. The problem is easy to see in 1D. Consider the model y_i = f(x_i) + error_i where `f' is a smooth function. If x_i only takes the values 0 and 1 then you really don't have much of a basis for estimating f.
- Simon Wood, Mathematical Sciences, University of Bath, Bath BA2 7AY - +44 (0)1225 386603 www.maths.bath.ac.uk/~sw283/
On Thu, 13 Dec 2007, zhijie zhang wrote:
Dear all, Following the help from gam(mgcv) help page, i tried to analyze my dataset with all the default arguments. Unfortunately, it can't be run successfully. I list the errors below. #m.gam<-gam(mark~s(x,y)+s(lstday2004)+s(slope)+s(ndvi2004)+s(elevation)+s(disbinary),family=binomial(logit),data=point) m.gam<-gam(mark~s(x,y,k=10)+s(lstday2004,k=10)+s(slope,k=10)+s(ndvi2004,k=10)+s(elevation,k=10)+s(disbinary,k=10),family=binomial(logit),data=point)
m.gam<-gam(mark~s(x.1,y.1,k=10)+s(lstday2004,k=10)+s(slope,k=10)+s(ndvi2004,k=10)+s(elevation,k=10)+s(disbinary,k=10),family=binomial(logit),data=point)
#?????? Errors: smooth.construct.tp.smooth.spec(object, data, knots) : A term has fewer unique covariate combinations than specified maximum degrees of freedom. #========================# Descriptions for my dataset #========================# There are 1 response variable "mark" (1-case,0-control), and 7 explanatory covariables. x/y are spatial coordinates, lstday2004, slope, ndvi2004, elevation: continuous variables; disbinary : binary variable. Is there any problems with the above codes? How should i solve it? Any help or suggestions are greatly appreciated. -- With Kind Regards, oooO::::::::: (..)::::::::: :\.(:::Oooo:: ::\_)::(..):: :::::::)./::: ::::::(_/:::: ::::::::::::: [***********************************************************************] Zhi Jie,Zhang ,PHD Tel:+86-21-54237149 Dept. of Epidemiology,School of Public Health,Fudan University Address:No. 138 Yi Xue Yuan Road,Shanghai,China Postcode:200032 Email:epistat at gmail.com Website: www.statABC.com <http://www.statabc.com/> [***********************************************************************] oooO::::::::: (..)::::::::: :\.(:::Oooo:: ::\_)::(..):: :::::::)./::: ::::::(_/:::: :::::::::::::