Hi
I am using Stata 9.2 on windows.
I am fitting an xtpoisson model to unbalanced panel data (n counts of death
over T months), with a grouping variable called unit that signifies the ICU
where the data come from. E.g
obs_rrt T unit
0 5 4
3 6 4
2 7 4
4 8 4
3 9 4
1 10 4
3 2 3
1 3 3
1 4 3
1 5 3
0 6 3
1 7 3
Question 1.
When I specify
tis T
my understanding is that this does not explicitly model T in the model (I
want to model the death rate in relationship to time, amongst other things),
and I would have to specify T in the command line to do this. Is this
correct?
Question 2.
I would like to specify T and some other exposure covariates as fixed
effects, and unit as a random effect in the model. If I specify all of these
as independent variables in the command line, and then use the re option,
how can I tell which is modelled as fixed, and which is modelled as random?
Thanks,
Mark Marshall
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