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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 10:46:05 +0100
Hi,
You can use "margins, at"
webuse margex
logit outcome i.sex i.group,or
margins, at(sex==1 group==1)
OR, if you use xi
xi: logit outcome sex i.group,or
margins, at(sex==1 _Igroup_2 ==0 _Igroup_3==0 )
BW,
Abdelouahid
> Date: Wed, 24 Oct 2012 03:18:11 -0500
> To: [email protected]; [email protected]
> From: [email protected]
> Subject: Re: st: Adjusted Prevalence from Logistic models
>
> At 01:18 AM 10/24/2012, Dean Eurich wrote:
> >Hi all,
> >
> >A simple question. If I run a logistic model:
> >
> >logistic BB age sex rural
> >
> >I get the OR for the effect of rural (which is a flag for rural=0 or
> >urban=1 dwelling) on the use of beta blockers (medication used to
> >treat cardiovascular disease).
> >
> >A reviewer has asked for us to present the adjusted prevalence for
> >the use of BB by rural and urban status. I am not to sure how to do this.
> >
> >I assume I could use the 'margin' command.
> >
> >So would it be as simple as
> >
> > margins rural, atmeans
> >
> >(Although I realize I could do it as specific levels of sex and age as well)
> >
> >Thanks
> >
> >Dean
>
> I'm not totally sure how you want to adjust. But if you want to use
> -margins- you should use factor variable notation, e.g.
>
> logistic BB age i.sex i.rural
> margins rural, atmeans
>
> In general, I am not crazy about the atmeans option, and I especially
> don't like it when you have a variable like sex in the model. You'll
> be plugging in something like .5 for sex (the average person is half
> male, half female?) I'd rather use the default -asobserved- or plug
> in specific values or ranges of values for the other variables. For
> some highlights of what you can do with margins, see
>
> http://www.nd.edu/~rwilliam/stats/Margins01.pdf
>
> As a sidelight, when you say rural=0 or urban=1, that sort of sounds
> to me like heads I win, tails you lose. Aren't rural=0 and urban=1
> the same thing?
>
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
> OFFICE: (574)631-6668, (574)631-6463
> HOME: (574)289-5227
> EMAIL: [email protected]
> WWW: http://www.nd.edu/~rwilliam
>
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