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# Re: st: RE: graph interaction curve

 From Fabio Zona To statalist@hsphsun2.harvard.edu Subject Re: st: RE: graph interaction curve Date Mon, 28 Feb 2011 12:14:52 +0100 (CET)

```Hi Maarten
I do have Stata 11. So, no penance for me! However, I find the entry by Bill Gould useful anyway!
Thanks
Fabio

----- Messaggio originale -----
Da: "Maarten buis" <maartenbuis@yahoo.co.uk>
A: statalist@hsphsun2.harvard.edu
Inviato: Lunedì, 28 febbraio 2011 12:05:57 GMT +01:00 Amsterdam/Berlino/Berna/Roma/Stoccolma/Vienna
Oggetto: Re: st: RE: graph interaction curve

> > > I am really having hard time to graph an interacion between
> > > a curve and a linear moderator.
> > >
> > > this is the equation:
> > >
> > > Y = a + X +  X^2  + moderator  +  X * moderator
> > >
> > > Is there an easy way to graph the curve and see how it
> > > changes, for different values of the moderator?

> > The short answer is No. There isn't an easy way, but there
> > is a way to solve this nevertheless. Maarten already posted
> > a concrete example at
> >
> > http://www.stata.com/statalist/archive/2011-02/msg01240.html

--- On Fri, 25/2/11, Fabio Zona asked again:
> does this solution work only with the functions c. ## ??
> can I calculate the interactions as products of variables
> (standardized variables) and the apply this method? If so,
> why doesn't it work with me?

I have written this example up as a Stata tip and submitted it
to the Stata Journal. A pre-publication draft can be seen at:

At that site there are also other examples and translations of
these examples to Stata < 11 (but >= 8). That should get you
started.

-- Maarten

Ps. if the problem was that you did not have Stata 11, then
you should have told us from the begining. The statalist FAQ
clearly states that we will assume that you have the latest
version of Stata when you do not tell us what version of
Stata you are using. If that was the case then as penance I
suggest you read the entire FAQ three times plus two times
this entry by Bill Gould:

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------

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```