[R] lme nesting/interaction advice

[Federico Calboli]

On 12 May 2008, at 09:29, Dieter Menne wrote:

> Federico:
>
> First, mixed models are different from "standard 101 Anova", and  
> quite a lot
> of the nesting stuff I used to ponder about 30 year ago when I started
> teaching this is no longer relevant and works implicitely when you  
> code the
> parameters correctly.
>
>
>>> with effect3 being random (all all the jazz that comes from this  
>>> fact). I
> fully apprecciate that the only reasonable F-tests would be for  
> effect1,
> effect2 and effect1:effect2, but there is no way I can use lme to  
> specify
> such simple thing without getting the *wrong* denDF. >>
>
> Good to know that you are sure what is "right"; probably == SAS.  
> Since most
> people active in the lme-business have read
>
> http://wiki.r-project.org/rwiki/doku.php?id=guides:lmer-tests
>
> http://finzi.psych.upenn.edu/R/Rhelp02a/archive/76742.html
>
>
> carefully, you might be rather lonely.

I will. While I do, feel free to have a look at Appendix A.3 (page  
App6, at the end of the book) of the Zar 'Biostatistical Analysis',  
IV ed, second table from the top. That's where I get the feeling for  
what's right or wrong. I surely cannot get it from SAS because I  
never had it. I never had the budget for it, so much so I had to lear  
how to use R from the start because it was free and that was the  
budget of my department had for stats software

All in all, if you feel statistical analysis has moved forth from  
such humble beginnings (the book I mean, not SAS), and you can  
convince of that every ref for every paper you submit, please do tell  
me how you do it, it would be more valuable than knowing how to fit  
my model.

Cheers,

Federico





--
Federico C. F. Calboli
Department of Epidemiology and Public Health
Imperial College, St. Mary's Campus
Norfolk Place, London W2 1PG

Tel +44 (0)20 75941602   Fax +44 (0)20 75943193

f.calboli [.a.t] imperial.ac.uk
f.calboli [.a.t] gmail.com