[R] [R-pkgs] New version of lme4 and new mailing list R-SIG-mixed-models

John Maindonald john.maindonald at anu.edu.au
Sun Jan 28 12:55:15 CET 2007

Dear Douglas -
I have tried several fits that relate to ch 10 of the 2nd edition of  
Maindonald & Braun.  In two cases a fit that does not currently  
converge with lmer does now converge with lme2.  In one case where I  
took logs in order to get convergence (the data did not really demand  
it), I can now get away without taking logs.  Basically, none of the  
problems that I had to work around when I did the calculations for  
that chapter have surfaced.  An exercise that had been problematic  
now converges without apparent problem.

In one case CPU time was reduced by a factor of around 3.  In one  
case where I formerly could not get convergence, the reduction (to  
termination of the calculations) was by a factor of around 10.  The  
results seems similar, with a small increase in the loglikelihood  
(perhaps ~0.5; I have not checked very carefully) in some cases.  If  
you want more detail, I will provide it.

It looks a huge improvement.  I am sure that R users will be duly  
grateful for your efforts.
John Maindonald.

John Maindonald             email: john.maindonald at anu.edu.au
phone : +61 2 (6125)3473    fax  : +61 2(6125)5549
Centre for Mathematics & Its Applications, Room 1194,
John Dedman Mathematical Sciences Building (Building 27)
Australian National University, Canberra ACT 0200.

 > sessionInfo()
R version 2.4.1 Patched (2007-01-17 r40518)


attached base packages:
[1] "stats"     "graphics"  "grDevices" "datasets"  "utils"      
[7] "base"

other attached packages:
        DAAG        MASS        lme4      Matrix     lattice
      "0.91"    "7.2-31" "0.9975-11"  "0.9975-8"   "0.14-16"

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