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From | Maarten Buis <maartenlbuis@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Simple slope analysis for non-linear models |
Date | Mon, 25 Mar 2013 10:30:22 +0100 |
On Sun, Mar 24, 2013 at 11:40 AM, Ebru Ozturk wrote: >I followed your suggestion and it seems that I want this derivative E( y |X, y ≥ 0). ok > In my model, I have one interaction term (dummy X continuous-ranges from 0 to 10) and other Xs. This is sentence full of contradicotry statements: Do you have one or many interaction terms? Is your key variable a single indicator (dummy) variable, 10 indicator variables, or continuous? >I would like to plot the values of true interaction effect and implied z-statistic value at each observation. After doing that I would like to show the value and significance of X’s marginal effect at selected values of the moderator Z (low, mean and high). I use Stata 10. There is no such thing as a "true interaction effect". I presume you are looking for a cross partial derivative or discrete difference (depending on whether your variables are continous or categorical). As far as I know there is no program that does this kind of computation for -tobit-, so you'll need the general purpose commands -predictnl- and -adjust- for that in Stata 10. So, you'll need to look up the appropriate formulas and probably do the derivatives yourself. For such computations I often combine doing the derivations by hand and using <http://www.quickmath.com/>. After those computations you can feed the results to -predictnl- or -adjust-. I realize you would have liked the answer to be in the form of a command rather than some general tips on how to write a program that does what you want to do. But if no one wrote the program before, then that is the only answer possible. I could have written the program for you, but that is too big time investment on my part. I only do things like that if I am also interested in that problem. In this case I consider this way of thinking about interaction terms a dead end, so I am not going to invest time in it. > But the problem is in journals I use they never mention which Tobit intepretation they implement so that's why I am struggling. So they report differences/changes in predicted outcome without defining what the outcome is? That seems a bit problematic to me. Hope this helps, Maarten --------------------------------- Maarten L. Buis WZB Reichpietschufer 50 10785 Berlin Germany http://www.maartenbuis.nl --------------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/