--- Urspr??ngliche 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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