Hello, We are attempting to compare some results using lme and lme4. I'm relatively new to this so could well be asking questions that are overly simplistic or naive, if so please inform. We have an example that works with nlme(lme) and specifying the weights as the function varConstPower, however when we try to do a slightly more specific analysis using lme4(lmer) it doesn't seem to have the varConstPower function built it. Is in nonsensical to build it into lme4? It might well have some shortcomings/compromises. Is there a way we could accomplish the same thing with lme4 via some R coding or any other method? All suggestions most welcome. Thanks Jim Jim Maas University of East Anglia
lme vs lme4
2 messages · Jim Maas, Ben Bolker
Jim Maas <j.maas at ...> writes:
We are attempting to compare some results using lme and lme4. I'm relatively new to this so could well be asking questions that are overly simplistic or naive, if so please inform. We have an example that works with nlme(lme) and specifying the weights as the function varConstPower, however when we try to do a slightly more specific analysis using lme4(lmer) it doesn't seem to have the varConstPower function built it. Is in nonsensical to build it into lme4? It might well have some shortcomings/compromises. Is there a way we could accomplish the same thing with lme4 via some R coding or any other method?
It's not nonsensical, but it's way down the priority list for the lme4 developer(s), so I wouldn't hold your breath. I guess my question would be: what are the advantages of lme4 for your particular analysis (i.e. reasons to use lme4 instead of nlme)? The main ones that I can think of are (1) speed and (2) handling of crossed random effects. For #1, you might consider ASREML-R (I'm not particularly familiar with it, and I mostly work with GLMMs, for which ASREML has some lacunae, but I've been impressed by some of the posts at http://www.quantumforest.com/ ...) For #2, it is *possible* [although clunky/slow] to implement crossed random effects in (n)lme. See http://glmm.wikidot.com/faq#lme-comp (for example)