Dear all, I am confused.
I have encountered some strange behaviour of gls
> data(co2)
> co2.y <- aggregate(co2,1,mean)
> co2.y.data <-
data.frame(co2=as.numeric(co2.y),year=seq(1959-1980,along=co2.y))
> co2.1.gls <- gls(co2~year+I(year^2), co2.y.data)
> co2.2.gls <- update(CO2.1.gls, corr=corAR1())
> summary(CO2.2.gls)
> plot(CO2.2.gls)
plot shows standardized residuals that range between 0.007 and -0.005.
summary(CO2.2.gls) shows results very different from summary(CO2.1.gls).
residual standard error seems to be badly estimated.
Are the data a pathological case? or am I doing something wrong?
Thanks in advance for any help.
(I was planning to use this example in a course...)
Pedro.
--
=================================================================Pedro J. Aphalo
Department of Biological and Environmental Science
University of Jyv?skyl?
P.O. Box 35, 40351 JYV?SKYL?, Finland
Phone +358 14 260 2339
Mobile +358 50 3721504
Fax +358 14 260 2321
mailto:pedro.aphalo at cc.jyu.fi
http://www.jyu.fi/~aphalo/ ,,,^..^,,,
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