[R-sig-ME] Bleeding edge lme4 (or lme4a) plus DF estimation

[Joehanes, Roby (NIH/NHLBI) [F]]

Hi,

I learned about the impending release of the new version of lme4 (or lme4a) from Dr. Bates' post here:
https://stat.ethz.ch/pipermail/r-sig-mixed-models/2012q1/007499.html

Firstly, just to make sure, is this based on lme4a? I have the source tarball of lme4a 0.999375-65 and found that a new optimizer, BOBYQA, is now in use, instead of the nlminb. The announcement above also mentioned the same change. So, I suspect that the older lme4 is supplanted with lme4a. Is this true?

Secondly, I would like to get a source tarball of the latest bleeding edge release to play with (or even read-only SVN access). I found from some sniff tests the lmer outputs of lme4a to be closely matched with those of SAS than those of the lme4 (with nlminb optimizer), except for the lack of p-values. I would love to play with the new version and even give you comparisons with the old version. The problem I am facing with lme4a 0.999375-65 is that it sometimes crashes (core dumps).

Thirdly, I also would love to see the Satterthwaite or Kenward-Rogers DF estimation. I would like to try to add these features into lme4, if you will. I don't know much about the formulas to compute the DFs from quantities output by lmer / glmer. Any pointers?

Thank you.

Sincerely,
Roby