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Re: st: conditional test after logistic regression


From   Ricardo Ovaldia <ovaldia@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: conditional test after logistic regression
Date   Wed, 14 Apr 2010 08:47:22 -0700 (PDT)

Thank you Maarten. That is what I thought, but I am not sure that I want conditioning on y. The article that I am reading states the null in terms of beta - Ho: (Bx|By)=0 

Would your answer change if y=x^2?

So that the model would be:

logistic case x x2

where x2=x^2

and the null is now,  Ho: (Bx2|Bx)=0 ?

Ricardo

Ricardo Ovaldia, MS
Statistician 
Oklahoma City, OK


--- On Wed, 4/14/10, Maarten buis <maartenbuis@yahoo.co.uk> wrote:

> From: Maarten buis <maartenbuis@yahoo.co.uk>
> Subject: Re: st: conditional test after logistic regression
> To: statalist@hsphsun2.harvard.edu
> Date: Wednesday, April 14, 2010, 10:36 AM
> --- On Wed, 14/4/10, Ricardo Ovaldia
> wrote:
> > If I fit:
> > 
> > . logistic case x y
> > 
> > I can test the null Ho:Bx=0, By=0 using:
> > 
> > . test x y
> > 
> > How can I test the null Ho: (Bx|By)=0 ?
> 
> I am guessing you want to condition on y 
> an not on By. In that case the answer can 
> be pretty easy: you haven't included an 
> interaction term between x and y, so that 
> is just
> 
> text x
> 
> However, this will only work if you are
> interested in effects in terms of odds
> ratios or log odds ratios. Things get 
> more complicated when you want to look
> at marginal effects.
> 
> Hope this helps,
> Maarten
> 
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
> 
> http://www.maartenbuis.nl
> --------------------------
> 
> 
>       
> 
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