[R] lme model: Error in MEEM

[Christoph Lehmann]

sorry, RT had an error in raw data and was treated as a factor. after
correction of the raw data (RT is numeric) now it works fine.

thanks a lot
christoph
> --- Ursprüngliche Nachricht ---
> Von: Douglas Bates <dmbates at gmail.com>
> An: Christoph Lehmann <christoph.lehmann at gmx.ch>
> Kopie: r-help at stat.math.ethz.ch
> Betreff: Re: [R] lme model: Error in MEEM
> Datum: Thu, 18 Aug 2005 08:29:52 -0500
> 
> On 8/18/05, Christoph Lehmann <christoph.lehmann at gmx.ch> wrote:
> > Hi,
> > We have data of two groups of subjects: 32 elderly, 14 young adults. for
> > each subject we have 15 observations, each observation consisting of a
> > reaction-time measure (RT) and an activation maesure (betadlpcv).
> > since we want to analyze the influence of (age-)group and RT on the
> > activation, we call:
> > 
> > lme(betadlpcv ~ RT*group, data=our.data, random=~ RT |subject)
> > 
> > this yields:
> > Error in MEEM(object, conLin, control$niterEM) :
> >         Singularity in backsolve at level 0, block 1
> > In addition: Warning message:
> > Fewer observations than random effects in all level 1 groups in:
> > lme.formula(betadlpcv ~ RT * group, data = patrizia.data, random = ~RT |
> > 
> > what's the problem here?
> 
> It seems that you only have one observation per subject and you are
> trying to estimate a model with two random effects per subject plus
> the per-observation noise term.  These terms are completely
> confounded.
> > 
> > thanks for your kind help
> > christoph
> > 
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