[NMusers] "Connect the dots" approach for a time-varying covariate

Dear NMusers,
I wish to model a biomarker that is controlled by a time-varying =
variable. The temporal pattern of this time-varying variable is =
irregular which makes a parametric description of its profile somewhat =
difficult. I am hoping to use a "connect the dots" approach for this =
exercise i.e. linear interpolation for the time-varying variable in =
between the observation. I believe there are suggestions on the users =
net to modify the dataset to complete slopes and intercepts for each =
time interval. I was wondering if there is a simpler way to compute the =
linear interpolation on the fly within the control stream. Finally, the =
complicating issue is that the biomarker of interest needs an =
initialization of it's compartment since it doesn't start at zero.

I would greatly appreciate if someone has a code and example dataset for =
such an exercise.

Thanking the group in advance...Mahesh




Received on Tue Jan 15 2008 - 16:52:44 EST