Hi Gustavo,

 

Thanks for your answer. If I understood, you mean that a random regression
model is a mixed model with random intercept only. However, in the current
literature (at least in ecology), random regressions are used to estimate
individual reaction norm components (see Dingemanse et al 2009 TREE
"Behavioural reaction norms: animal personality meets individual plasticity"
or Nussey et al 2007 Journal of Evolutionary Biology "The evolutionary
ecology of individual phenotypic plasticity in wild populations") and in
that case, it seems to me that both the intercept and the slope are allowed
to vary between individuals. Am I wrong? Thus, if I fit a model with a
behavioural trait as the dependent variable and an environmental gradient as
the independent variable and that I allow the intercept and slope of the
regression to vary between individuals, it is of course a mixed model but it
also fits into the categories "random regression model" and "animal model".
Right?

 

Cheers,

 

Amelie

 

  _____  

From: Gustavo Betini [mailto:betinig@uoguelph.ca] 
Sent: Monday, August 09, 2010 2:54 PM
To: amelie.lescroel@univ-rennes1.fr
Subject: Fwd: [R-sig-ME] Clarification needed about the terminology used
when talking about mixed models

 

Hi, Amelie,

a random regression model is a model with random and fixed effects (i.e.
mixed model) that 

allows for a random shift around the intercept while the slope is kept at a
fixed point. Take a look at Zuur et al. 2009, chapter 5. 
An animal model is a mixed model where individual identity is entered as a
random effect. This type of model  estimates the genetic component of
phenotypic variation. See Wilson et al. 2010 An ecologist's guide to the
animal model.

Cheers,

Gustavo



-------- Original Message -------- 


Subject: 

[R-sig-ME] Clarification needed about the terminology used when talking
about mixed models


Date: 

Mon, 9 Aug 2010 14:27:55 +0200


From: 

Amelie Lescroel  <mailto:amelie.lescroel@univ-rennes1.fr>
<amelie.lescroel@univ-rennes1.fr>


To: 

 <mailto:r-sig-mixed-models@r-project.org>
<r-sig-mixed-models@r-project.org>

 

Hello,
 
 
 
Could someone give me a clear definition of what a "random regression model"
is and what are the differences between a mixed model, a random regression
model and an animal model? I'm beginning to be lost among the multiple
designations. 
 
 
 
Thanks,
 
 
 
Amelie
 
 
 
 
 
 
 
 
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