Re: st: Change reference group in logistic regression

[Morten Støver <morten.stover@ntnu.no>]

Hello. I don't have Stata 11, but I did it like Maarten L. Buis, and it 
worked. Don't know what I did wrong the first time.
Thanks!
Morten S

Michael N. Mitchell wrote:
> Dear Morten
>
>   If you are using Stata 11, you can get rid of the xi: prefix and 
> specify the omitted group like this...
>
> logit foreign ib3.rep78
>
>   which says that -rep78- is an indicator variable, and the baseline 
> (omitted) group is 3. Or you can say
>
> logit foreign ib4.rep78
>
>   and the fourth group is the omitted group.
>
> The -fvset- command can be used to permanently change the reference 
> group (like the -char- command).
>
> I hope that helps,
>
> Michael N. Mitchell
> Data Management Using Stata      - 
> http://www.stata.com/bookstore/dmus.html
> A Visual Guide to Stata Graphics - 
> http://www.stata.com/bookstore/vgsg.html
> Stata tidbit of the week         - http://www.MichaelNormanMitchell.com
>
>
>
> On 2011-02-03 6.57 AM, Maarten buis wrote:
> > --- On Thu, 3/2/11, Morten Stover wrote:
> > > I want to change reference group doing a logistic
> > > regression analysis on highest level of education and
> > > future work disability. The data is coded 1=primary,
> > > 2 =secondary and 3=tertiary, and I would like tertiary
> > > to be the reference group. I've done this in cox
> > > regression using char and [omit], but I can't get this
> > > to work in log reg.
> >
> > I am assuming you are using the -xi- prefix. I cannot
> > replicate your problem. The example below works as
> > expected.
> >
> > *--------- begin example ----------
> > sysuse auto, clear
> > recode rep78 1/2=3
> >
> > char rep78[omit] 5
> > xi: logit foreign i.rep78
> > *----------- end example -----------
> >
> > Can you change the example above such that it reproduces
> > your problem? Seeing the problem on your own computer in
> > examples like that really help in diagnosing the problem.
> >
> > -- Maarten
> >
> > --------------------------
> > Maarten L. Buis
> > Institut fuer Soziologie
> > Universitaet Tuebingen
> > Wilhelmstrasse 36
> > 72074 Tuebingen
> > Germany
> >
> > http://www.maartenbuis.nl
> > --------------------------
> >
> >
> >
> >
> > *
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--
Morten Støver
MA, PhD Student
Department of Public Health and General Practice
Faculty of Medicine 
Norwegian University of Science and Technology
Medisinsk teknisk forskningssenter
N-7489 Trondheim
Tel +47 73597525

*
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