[R-sig-ME] lme vs. lmer
bolker at ufl.edu
Tue Sep 29 20:02:33 CEST 2009
Christopher David Desjardins wrote:
> I've started working through Pinheiro & Bates, 2000 and noticed the use
> of lme from the nlme package. I am curious if lmer from lme4 has
> superseded lme or if lme still holds its own? The reason I ask is that I
> have taken a few classes where we've solely used lmer and just read
> about lme today. If both functions are on equal footing, can the
> p-values from lme be trusted?
You should read the extended discussion of p-values, degrees of
freedom, etc. that is on the R wiki (I think) and referenced from the R
FAQ. At least in my opinion, (n)lme is still fine (and indeed necessary
at this stage for fitting heteroscedastic and correlated models). The
df/p-value estimates, however, are "use at your own risk" -- you'll have
to read the literature and decide for yourself.
I still think there's room for someone to implement (at least)
Satterthwaite and (possibly) Kenward-Roger corrections, at least for the
sake of comparison, but I'm not volunteering.
Associate professor, Biology Dep't, Univ. of Florida
bolker at ufl.edu / www.zoology.ufl.edu/bolker
GPG key: www.zoology.ufl.edu/bolker/benbolker-publickey.asc
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