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RE: st: Adjusted Prevalence from Logistic models
From
Abdelouahid Tajar <[email protected]>
To
statalist <[email protected]>
Subject
RE: st: Adjusted Prevalence from Logistic models
Date
Wed, 24 Oct 2012 12:15:04 +0100
Hi,
You get the same result though!
margins, at(sex==1 _Igroup_2 ==0 _Igroup_3==0 )
uses ,as I understand, sex==1 and group=reference, no?
with xi: margins uses dummy variables created by xi.
Could you please explain why it is dangerous in the case where there is no interaction in the model.
Thanks,
Abdelouahid
> Date: Wed, 24 Oct 2012 11:56:04 +0200
> Subject: Re: st: Adjusted Prevalence from Logistic models
> From: [email protected]
> To: [email protected]
>
> On Wed, Oct 24, 2012 at 11:46 AM, Abdelouahid Tajar wrote:
> > OR, if you use xi
> >
> > xi: logit outcome sex i.group,or
> >
> > margins, at(sex==1 _Igroup_2 ==0 _Igroup_3==0 )
>
> That is dangerous: -margins- needs to know about categorical variables
> and especially interactions in order to work well. It gets that
> information from the way you use factor variables but not from -xi:-.
> By using -xi:- instead of factor variables you are not giving
> -margins- the information it needs to work properly. So do not mix
> -xi:- with -margins-.
>
> -- Maarten
>
> ---------------------------------
> Maarten L. Buis
> WZB
> Reichpietschufer 50
> 10785 Berlin
> Germany
>
> http://www.maartenbuis.nl
> ---------------------------------
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