lme vs. lmer, how do they differ?

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lme vs. lmer, how do they differ?

John Sorkin
windows Vista
R 2.10.1

What is the difference (or differences) between lme and lmer? Both appear to perform mixed effects regression analyses.
Thanks
John


John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
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GRECC (BT/18/GR)
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Re: lme vs. lmer, how do they differ?

slre
>>> "John Sorkin" <[hidden email]> 10/09/2010 13:21:09 >>>
>What is the difference (or differences) between lme and lmer? Both
appear to perform mixed effects regression analyses.

>From a user's point of view:
- lme only accepts nested random effect; lmer handles crossed random
effects
- lme has a convenient methof of handling heteroscedasticity; lmer
doesn't.
- lme gives you p-values; lmer doesn't (there is explanation of why at
https://stat.ethz.ch/pipermail/r-help/2006-May/094765.html which, I
guess, should not be all that reassuring for lme users either)


Steve Ellison


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Re: lme vs. lmer, how do they differ?

bbolker
In reply to this post by John Sorkin
John Sorkin <jsorkin <at> grecc.umaryland.edu> writes:

>
> windows Vista
> R 2.10.1
>
> What is the difference (or differences) between lme and lmer? Both appear to
perform mixed effects
> regression analyses.
> Thanks
> John
>

  in a nutshell:

  lmer is newer, much faster, handles crossed random effects well (and
generalized linear mixed models), has some support for producing
likelihood profiles (in the development version), and is under rapid development.
It does not attempt to estimate residual degrees of freedom and
hence does not give p-values for significance of effects.
  lme is older, better documented (Pinheiro and Bates 2000), more
stable, and handles 'R-side' structures (heteroscedasticity,
within-group correlations).

  r-sig-mixed-models is a good place for questions about these
packages.

  Ben Bolker

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