How to use lme4.0 with lmerTest?

Question

I am wondering if anyone has faced this issue before. I use the package lmerTest to run mixed-effects models in R because it has a handy way of providing p-values. This package by default loads the most current version of the lme4 package. However, the lme4 current version has some issues and it sometimes doesn't converge, so the lme4 developers have made available a new package (named lme4.0), which is a bugfix-only version of the old pre-1.0 lme4. This works great, and the models usually converge, so that is what I use to analyze my data.

I would like to have lmerTest but have it load lme4.0 instead of the current version of lme4.Does anyone know how to achieve this?

Thanks for your help!

Answer 1

This isn't really feasible without serious hacking: essentially, take an older version of lmerTest, download the source, hack it to look for lme4.0 rather than lme4, and install locally. Or download (from the CRAN archives) and install older versions of lme4 and lmerTest (and pbkrtest: maintaining an archaic setup will get progressively more difficult, and you will have to backport or forego bug fixes as they appear in newer versions).

Since many of the problems with new lme4 have been cleaned up with the switch in default optimizers from Nelder-Mead to BOBYQA, my advice would be to run a range of comparisons between lme4.0 and lme4, convince yourself that there are no problems (and send information about persistent problems to the lme4 maintainers, who would greatly appreciate it!), and move on to the new version.