Date: Mon, 19 Jul 2004 07:29:36 -0700
Reply-To: jeremie guedj <jeremie.guedj@ISPED.U-BORDEAUX2.FR>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: jeremie guedj <jeremie.guedj@ISPED.U-BORDEAUX2.FR>
Subject: fit differential equation proc model
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I have the following problem with the "proc model"
I try to estimate parameters of a system of ODE and I have 2 problems
- In a first time, I want to simulate my data with known parameters,
add a noise, take a sample of these data and see if I can recover the
Moreover, the variance of the noise is supposed to be known.
How can I specifiate that this variance is known ?
I tried the option "h.parameters=sigma" but the results are not well.
- I would like to use the maximum likelihood.
There is the option "fiml".
But the data that I have to fit are not directly related to the system
of ODE but are a combination of them. For example, if my system is :
data to fit are ln(f) and f+g.
So I have an error message ; it seams that you can use fiml only if
data to fit are directly related to the system of ODE.
Is it right ?
Thank you in advance