[R] lme model: Error in MEEM

From: Christoph Lehmann <christoph.lehmann_at_gmx.ch>
Date: Thu 18 Aug 2005 - 22:38:02 EST

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?

thanks for your kind help

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Received on Thu Aug 18 22:44:53 2005

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