[R] mixed model nested ANOVA

Andrew Robinson A.Robinson at ms.unimelb.edu.au
Fri Dec 12 22:21:19 CET 2008

Hi Sebpe,

the analysis of the data that you describe could be a complex and
lengthy process, in which decisions that you are confronted by are
affected by previous decisions that you have made.  I recommend
obtaining the assistance of a statistician, preferably a local one
whose door you can knock on.  If you are unable to do so then I
suggest that you borrow/buy a copy of the Pinheiro and Bates book,
which documents lme() and its friends, and study it carefully,
especially the worked examples.

Good luck!


On Fri, Dec 12, 2008 at 03:13:06PM +0000, Sebpe De Smedt wrote:
> Hi,
> I'm working on leaf characteristics of trees. Each tree is characterised by
> about 10 leaf traits.
> The trees were sampled at 9 different locations (about 20 to 30
> trees/location, NOT balanced), grouped in 3 different climatic zones
> (Sahelian, Soudanian and Guinean) (NOT balanced).
> Further, each tree is characterised by some degree of human pressure
> (mutilation degree), in total 4 different degrees were defined (NOT
> balanced).
> In the dryer zones, the trees are under a much higher human pressure than in
> the more humid climatic zones, "zone" and "mutilation degree" are thus
> strongly correlated.
> I want to know how "zones" (fixed effects, climate interests me) and
> "locations" (nested in "zones", random effects, location doesn't interests
> me) are influencing the leaf traits (say for example "SLA"). Further, also
> human pressure is affecting leaf traits so I want to characterise the
> influence of "mutilation degree" (fixed effects) on "SLA".
> I found some interesting information, but still, I am not be able to analyse
> the data properly. I think I have to use the function lme() or lme().
> Can anyone tell me which function and command I have to use? And how I can
> produce an ANOVA table?
> Thanks in advance,
> Sebpe De Smedt
> 	[[alternative HTML version deleted]]
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Andrew Robinson  
Department of Mathematics and Statistics            Tel: +61-3-8344-6410
University of Melbourne, VIC 3010 Australia         Fax: +61-3-8344-4599

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