Bedankt John, dit werkt wel.
Overigens staat er een heel klein foutje in help desrep: "Aso see" ipv
also...
Maar ja, misschien vallen alleen Nederlanders daarover, niet echt
belangrijk dus.
Groet, Annelies
John Hendrickx wrote:
>
> Typing i.agegrp|durastay will create dummmies for the main effect of
> agegrp and interactions between agegrp and durastay as a continuous
> variable, but no main effects of durastay. But that isn't what the
> original poster wanted.
>
> You can use -desmat- for problems like this:
>
> desmat: poisson patient origin age.durstay, exp(ptime)
>
> This will estimate a model with main effects for origin and an
> interaction between age and durstay, but no main effects of age and
> durstay. But what you're perhaps really interested in is
>
> desmat: poisson patient origin age durstay age3.durstay3, exp(ptime)
>
> Where age3 and durstay3 are the variables recoded to 3 categories.
>
> The latest version of -desmat- is available at SSC. Type -ssc
> describe desmat- for more information.
>
> Hope this helps,
> John Hendrickx
>
> --- Jonathan Beck <[email protected]> wrote:
> > typing i.agegrp|durastay (without "i."before durastay) should give
> > you main effects for durastay plus the interactions with agegrp,
> > but
> > no main effects for agegroup.
> >
> > I suppose you read the right thing in help, but got an error by
> > translating it to your varnames.
> >
> > Jonathan
> >
> > > 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]
> > > *
> > > * For searches and help try:
> > > * http://www.stata.com/support/faqs/res/findit.html
> > > * http://www.stata.com/support/statalist/faq
> > > * http://www.ats.ucla.edu/stat/stata/
> >
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
>
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--
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]
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
