[R] Sensibility analysis

[brunels@free.fr]

Hi everyone,
 
i'm actually working on a nonlinear mixed-effects model, and beginning the 
study of its sensibility.
It takes 35 input and gives a n*35 matrix of output as it's a growth model (n 
is the number of days of the growth period).
Well, I have to analyse the variation of the output in relation to the 
variation of the parameters of this models (first univariate then multivariate 
variation)  :  it's a sensibility analysis ( a french word-by-word 
translation ). 
So, I choose one parameter, increase its value, do it one more time and again, 
and for each of the 10 responses I have a curve of sensibility which i have to 
calculate numerically the derivative.
 I have read some books but none of them treated this scope in detail, so i 
wonder : 
    - what are the numeric differentation methods available in this case. Are 
they available on R?
    - which criteria to choose for the variation step of the parameters ?
    - do you have any reference of books i may consult ?
 
I'd be glad to receive any help from you all. Thanks.
 
the student i am bless your mailing-list
 
 

 
 
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