[R] use of covariates with nlmeODE

From: Jesus Frias <Jesus.Frias_at_dit.ie>
Date: Wed 16 Mar 2005 - 22:02:35 EST


Dear R-helpers,

        I have some problem with a model I am trying to run with nlmeODE. I have a covariate that I want to include in the model and I can't find in the documentation how to include it in the model so that it can calculate it.

>formula(trial)

PME ~ time | Ident

abcnoniso <- list(DiffEq=list(

                    debdt = ~ -ksol*pH*eb ,
                    desdt = ~ ksolref*pH*eb-kdegref*pH*es,
                    dpHdt= ~ -k*(pH-pHinf)
                    ),
                  ObsEq=list(
                    c1 = ~ 0,
                    c2 = ~ es,
                    c3 = ~ 0),
                  Parms=c("ksol","kdeg","k","es0","eb0"),
                  States=c("es","eb","pH"),
                  Init=list("eb0","es0",3))
abcnonisomodc <- nlmeODE(abcnoniso,trial)

The variable pHinf is a covariate that changes from experiment to experiment. The model does not take very well pHinf.

regards,

Jesus



Jesús María Frías Celayeta
School of Food Sci. and Env. Health.
Faculty of Tourism and Food
Dublin Institute of Technology
Cathal Brugha St., Dublin 1. Ireland
t +353 1 4024459 f +353 1 4024495
w www.dit.ie/DIT/tourismfood/science/staff/frias.html
-- 
This message has been scanned for content and 
viruses by the DIT Information Services MailScanner 
Service, and is believed to be clean.
http://www.dit.ie

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Received on Wed Mar 16 22:51:42 2005

This archive was generated by hypermail 2.1.8 : Fri 03 Mar 2006 - 03:30:48 EST