[R-sig-ME] specification of corAR1()

[Gavin Simpson]

On Wed, 2011-08-10 at 10:07 -0700, array chip wrote:
> Hi all, I am struggling to learn to use corAR1() correlation structure. Let me use the Machines data set from nlme package as an example:
> 
> I added a time variable to create a new dataset:
> 
> > Machines2<-cbind(Machines, time=c(1,2,3))
> 
> This one runs without any problem:
> 
> 
> > lme(score~Machine,data=Machines2,random=list(Worker=pdSymm(~0+Machine)),correlation=corAR1())

That's not what the first argument of corAR1() is for. Not the first
time that has caught someone out (there's at least you and me!).

G

> 
> But all of the following generated the same error message:
> > lme(score~Machine,data=Machines2,random=list(Worker=pdSymm(~0+Machine)),correlation=corAR1(~time))
> > lme(score~Machine,data=Machines2,random=list(Worker=pdSymm(~0+Machine)),correlation=corAR1(~time|Worker))
> > lme(score~Machine,data=Machines2,random=list(Worker=pdSymm(~0+Machine)),correlation=corAR1(~time|Worker/Machine))
> 
> "Error in abs(value) : Non-numeric argument to mathematical function"
> 
> Did I misunderstand something here?
> 
> Thanks very much!
> 
> John
> 
> _______________________________________________
> R-sig-mixed-models at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models

-- 
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
 Dr. Gavin Simpson             [t] +44 (0)20 7679 0522
 ECRC, UCL Geography,          [f] +44 (0)20 7679 0565
 Pearson Building,             [e] gavin.simpsonATNOSPAMucl.ac.uk
 Gower Street, London          [w] http://www.ucl.ac.uk/~ucfagls/
 UK. WC1E 6BT.                 [w] http://www.freshwaters.org.uk
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%