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Re: st: -graph twoway (function ...)- question
Thanks for this hint, I didn't know your app!
But, after having played around with it, I fear it is not possible to
have multiple probability lines in one graph? E.g. I would want to
show the change in the probability but for each of the three age
categories separately (but in one graph). Is this possible? Would I
need to deal with the -save- option? And last, it seem not possible to
display confidence intervals, right?
When I would like to display changes in probabilities, what else is
available as an option. I know the prvalue/praccum command which I
will try next. Any good input is welcomed, though!
Kind regards,
Andrea
P.S. In your help file, in the "examples" section, there is a line
"oprobpr mpg, adj(weight=2500, foreign=0)" while the option -adj- is
not discussed (and does not work).
On Jul 24, 2008, at 3:37 PM, Nick Winter wrote:
I don't have an answer to your specific question, but another way to
go is to plot predicted probabilities. My -oprobpr- package might
help for this. (-oprobpr- only works after -oprobit- not -probit-,
but oprobit will estimate the same model as probit if there are only
two response categories; just use the -categories()- option to
specify which response category you want plotted.
-Nick Winter
Andrea Bennett wrote:
Dear all,
I have estimated average marginal effects from a probit regression
with -margeff- and would like to generate a graph which plots the
marginal effects for 3 age categories (dummies) dependent on a
continuous variable called cont.
The model is as such:
y = b0 + b1*age2 + b2*age3 + b3*age2*cont +b4*age3*cont + b5*cont +
controls
As age2 and age3 are dummies, would the following graph command be
correct:
twoway (function age1 = _b[cont]*x, range(0 0.5)) (function age2 =
_b[age2] + (_b[cont] + _b[cont_age2])*x, range(0 0.5)) (function
age3 = _b[age3] + (_b[cont] + _b[cont_age3])*x, range(0 0.5))
The way I understand it, since I have now marginal effects I can
work equivalently to linear models. Then the above graph should be
correct, right? Further, this would also be correct when
introducing other interactions with -cont- as long as I am looking
at the marginal effects of age groups when -cont- changes?
Many thanks for your considerations,
Andrea
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--
--------------------------------------------------------------
Nicholas Winter 434.924.6994 t
Assistant Professor 434.924.3359 f
Department of Politics [email protected] e
University of Virginia faculty.virginia.edu/nwinter w
PO Box 400787, 100 Cabell Hall
Charlottesville, VA 22904
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* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/