Dear All, I just came across the same error message (running a gnls{nlme} model). [R-2.1.1 on Mac OS 10.4]
For a reproducible example, please download the file: http://mit.edu/costas/www/GR.txt and run the following: GR <- read.table("GR.txt",header=T) attach(GR) myyear <- year-1969 library(nlme) gnls4a <- gnls(fatalities/vehicles1000~a0*(vehicles1000/ population1000)^a1,start=c (a0=1,a1=1),data=GR,na.action=na.omit,correlation=corARMA(form=~myyear)) Thanks a lot, Costas On 10 Ιουν 2005, at 8:43 ΠΜ, Pamela McCaskie wrote: > Dear all > I am tryiing to fit the following lme with an ARMA correlation > structure: > > test <- lme(fixed=fev1f~year, random=~1|id2, data=pheno2, > correlation=corARMA(value=0.2, form=~year|id2), na.action=na.omit) > > But I get the following error message: > > Error in getGroupsFormula.default(correlation, asList = TRUE) : > "Form" argument must be a formula > > I have used this same form argument with differerent correlation > structures and it has worked fine. Does anyone know why it won't > recognise ~year | id2 (or even ~ 1 | id2) as a formula? > > Any help would be great > Pam > > -- > Pamela A McCaskie > BSc(Mathematical Sciences)(Hons) > > Western Australian Institute for Medical Research > University of Western Australia > SCGH Campus > Ground Floor, B Block > QE-II Medical Centre > Hospital Avenue, Nedlands > Western Australia 6009 > AUSTRALIA > Email: [EMAIL PROTECTED] > Phone: +61-8-9346 1612 > Mob: 0417 926 607 > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting- > guide.html > > -- Constantinos Antoniou, Ph.D. Massachusetts Institute of Technology Intelligent Transportation Systems Program 77 Massachusetts Ave., Rm. 1-249, Cambridge, MA 02139 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html