Re: st: multiple interaction effects

[Maarten buis <maartenbuis@yahoo.co.uk>]

--- On Fri, 20/8/10, Fabio Zona wrote:
> In my study I have three independent variables x1 x2 x3,
> and I have three hypotheses regarding the interactions of
> these variables with another fourth var z1.
> 
> Question: do I have to test the interaction effects
> separately (i.e., one single model for each interaction,
> that is, one regression for x1z1, a different regression for
> x2z1...)?
> Or do I need to test these three interactions effects in
> one single regression (i.e., in one single regression I
> include: x1z1 x2z1 x3z1)? What is the difference in terms of
> interpretation?
> Note: the three variables x1 x2 x3  refer to
> constructs realted to the same phenomenon

If x1 x2 and x3 are the cause of that phenomenon, than it
makes sense to use a model with parametrically weighted
covariates or a MIMIC model, see e.g.:

<http://www.maartenbuis.nl/wp/prop.html>

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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