Dear all, I am trying to bootstrap predictions from gnls models using the following code:
# a is the dataframe with which I am working; it contains the variables # response.variable,LD,L,G,P and F ### model=gnls(response.variable ~ a * LD/(b + LD), params = list(a + b ~ L), start = c(1,1,1,1), data=a) df=cbind(a,fit=predict(model,list(LD=1,L=0.5,G=0.5,P=0.46,F=2.2))) model.bootfunc=function(rs,i){ df$response.variable=df$fit+rs[i] as.numeric(predict(gnls(response.variable ~ a * LD/(b + LD), params = list(a + b ~ L), start = coef(model), data=df))) } rs=scale(resid(model),scale=F) (model.boot=boot(rs,model.bootfunc,R=1)) booted=boot.ci(model.boot,index=1,type=c("norm","basic","perc","bca")) ### The problem is that this code yields "NA" for the s.e. of the bootstrap statistics: Bootstrap Statistics : original bias std. error t1* 0.1651658 -0.020663364 NA t2* 0.1669592 -0.021759335 NA t3* 0.1676765 -0.001858686 NA t4* 0.1726982 -0.025321349 NA t5* 0.1658092 0.024721214 NA And hence the boot.ci function and others don?t work. Does anyone have an idea on that? Many thanks and best wishes Christoph -- Dr. rer.nat. Christoph Scherber University of Goettingen DNPW, Agroecology Waldweg 26 D-37073 Goettingen Germany phone +49 (0)551 39 8807 fax +49 (0)551 39 8806 Homepage http://www.gwdg.de/~cscherb1 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.