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Re: st: Would _sgmediation_ work for dichotomous dependent variable?


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Would _sgmediation_ work for dichotomous dependent variable?
Date   Sun, 1 Aug 2010 22:54:50 +0000 (GMT)

--- On Sun, 1/8/10, Bo MacInnis wrote:
> The help file of binary_mediation indicates that mediator
> variables shall be standardized. Is it a recommendation or a
> requirement? In my current study, unstandardized mediator
> seem to make more sense than standardized mediator.
> 
> Another question on effect size: I am an economist and
> trained in being interested in marginal effects rather than
> coefficients in the nonlinear model like logit or probit but
> I am working on project for a psychologist. Would the
> mediational analysis be extended to marginal effect rather
> than coefficients in the probit model? 

If I understand Phill's model correctly, he solves the problems
involved with non-linear models by declaring that we care
about the effects on the latent variable rather than the effects
on the probability or the odds. In that case the model becomes 
linear again.

This answers both your question: Yes, the standardization is
a requirement, because the scale of the latent variable is 
unidentified, so you need to fix it by standardizing. No, you
can't use this with marginal effects, because then the model
becomes non-linear again.

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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