[R] Mixed-effects model problem.

Peter Dalgaard BSA p.dalgaard at biostat.ku.dk
Thu Sep 6 08:20:06 CEST 2001

Rob Hyndman <Rob.Hyndman at buseco.monash.edu.au> writes:

> I'm trying to fit a mixed-effects model of the form
> Y = a + bX + cZ + e
> where X are fixed effects and Z are random. i.e., c is a vector of
> random coefficients with mean 0. There is no "grouping" variable such as
> would be used with longitudinal data.
> Can the nlme package handle this sort of thing? Although it is a simpler
> model than would be used with grouped data, I can't seem to convince
> lme() to fit it. It seems to want a grouping variable and I can't
> persuade it that there is no such thing.
> Any help would be appreciated.

It's been a while since I played around with this, but as far as I
remember there is no requirement that the grouping variable has more
than one group...

   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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