Dear all,
I might just look at the wrong place, but...
I'm performing a poisson regression like:
xi: poisson patient i.origin i.age i.durstay, exp(ptime)
with 7 agegroups and 9 groups for durstay.
I want to add an interaction between age and durstay, defined as
i.agegrp*i.durastay, for which I reallocated agegroups and durstay
groups to broader categories 3*3. Now of course, the only extra output
I'd like to see is the interactions, not the main effects.
The only thing I could find in "help" is:
i.varname1|varname3 creates dummies for categorical variable
varname1 and includes continuous variable varname3: all interactions
and main effect of varname3, but not main effect of varname1.
So I conclude from that, that if I would do i.agegrp|i.durastay, I would
get the interactions and the main effect of durastay? That doesn't
really help, so what character should be used for only interaction and
no main effect? the FAQ's and websearch didn't really guide me to the
right direction too.
I use stata 7
Thanks for any help!
Annelies
--
A.M. Vos
dept. of Public Health
Erasmus MC
University Medical Center Rotterdam
P.O. Box 1738
3000 DR Rotterdam
The Netherlands
Tel: +31 (10) 4087502
Fax: +31 (10) 4089449
email: [email protected]
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