[R] Significance of degrees of freedom in nlme

[Spencer Graves]

	  Your question begins, "Dear Dr. Bates", yet Bates does not appear as 
an addressee in the copy of your question that I recieved via r-help.  I 
will offer a couple of suggestions in the hopes that they might help 
you.  Since your question did not include enough detail for anyone to 
answer without additional information, I used 'RSiteSearch("gabriela 
escati peñaloza")' to find earlier posts that might be related.  This 
generated 14 hits, the most relevant of which seemed to be 
"http://finzi.psych.upenn.edu/R/Rhelp02a/archive/69466.html".  From 
this, I copy the following:  	

formula(my data.gd)
dLt ~ Lt | ID
TasavB<- function(Lt, Linf, K) (K*(Linf-Lt))
my model.nlme <- nlme (dLt ~ TasavB(Lt, Linf, K),
data = my data.gd,
fixed = list(Linf ~ 1, K ~ 1),
start = list(fixed = c(70, 0.4)),
na.action= na.include, naPattern = ~!is.na(dLt))

	  I assume something got garbled here, because constructs like "my 
data.gd" generate a 'syntax error' for me;  I therefore assume it is 
"my_data.gd" (with an underscore between "my" and "data.gd".)  Try the 
following:

sapply(my_data.gd, class)

	  What columns of my_data.gd are factors, and how do they relate to 
Linf and K?  You can explore this using "table".

	  If you would like more help from this listserve, please submit 
another post.  Before you do, however, PLEASE do read the posting guide! 
"www.R-project.org/posting-guide.html", and try some of the things 
suggested there.  In particular, if you haven't already, try RSiteSearch 
for "nlme degrees of freedom" and anything else that seems relevant to 
you.  Also, before your next post, I encourage you to try to develop the 
simplest, self-contained example that illustrates your question.  I 
believe you will more likely receive faster, more useful replies if you 
make it easier for people to help you.

	  hope this helps,
	  spencer graves

gabriela escati peñaloza wrote:

> Dear Dr. Bates,
> Thank you very much for your response. I had consulted
> the algorithm described in Pinheiro and Bates.
> However, what I don't understand (among other things)
> is why my two parameters appear to be estimated at
> different grouping levels (based on the DF values).
> Affect this different values of DF at the estimates
> parameters? The estimates fixed effects were get at
> the same level of grouping?
> I apreciate any response.
> 
> 
> 
> 
> Lic. Gabriela Escati Peñaloza
> Biología y Manejo de Recursos Acuáticos
> Centro Nacional Patagónico(CENPAT). 
> CONICET
> Bvd. Brown s/nº.
> (U9120ACV)Pto. Madryn 
> Chubut
> Argentina
> 
> Tel: 54-2965/451301/451024/451375/45401 (Int:277)
> Fax: 54-29657451543
> 
> 
> 	
> 
> 
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