[R] Problems with corARMA

[Pamela McCaskie]

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
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AUSTRALIA
Email:        pmccask at cyllene.uwa.edu.au
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