Dear List,

 

The question below did not produce any answers. I have checked again and
can not see how this might be a really stupid question, so If anyone can
point me in the direction of the right syntax (or explain that it is not
possible, or why it is a stupid question) I would be grateful. 

 

With thanks

Ric

 

Richard Coe

Principal Scientist - Research Methods

World Agroforestry Centre (ICRAF)

and

Statistical Services Centre

 

From: Coe, Richard (ICRAF-ILRI) 
Sent: 15 December 2009 09:56
To: 'r-sig-mixed-models@r-project.org'
Subject: nlmer model syntax

 

I am using nlmer to fit asymptotic regression models y = f(N)  to
grouped data. The following gives expected results:

 

model1<-nlmer(y~SSasymp(N,a,b,k)~a+b+k|siteyear, data=nresp,
start=c(a=3837,  b=37, k=.024))

 

Now I would like each of the parameters a, b and k to depend on
covariates F1 and F2, something like

 

a+b+k~ F1+F2 +(1+F1+F2|siteyear) 

 

I cannot find an example of nlmer models with such covariates so cannot
figure out the syntax for defining them. Any suggestions gratefully
received.

 

Ric

 

 

Richard Coe

Principal Scientist - Research Methods

 

+255 768 882 165 (Tanzania)

+254 733 629 515 (Kenya)

+ 44 773 410 4196 (UK and world wide)

 

World Agroforestry Centre (ICRAF)

www.worldagroforestrycentre.org

 

and

 

Statistical Services Centre, University of Reading

www.rdg.ac.uk/ssc 

 

 


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