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# Re: st: RE: graph on marginal effects and confidence intervals

 From Mirko To statalist@hsphsun2.harvard.edu Subject Re: st: RE: graph on marginal effects and confidence intervals Date Mon, 5 Apr 2010 12:15:34 +0100

```Here we go:

sysuse auto, clear
margins, dydx(weight) over(foreign) post
mat b=e(b)
gen x = _n in 1/3
gen mem = b[1,1] in 1
replace mem= b[1,2] in 2
twoway (rscatter mem mem x), xlabel(1(1)2) yline(0)

On 5 April 2010 12:10, Martin Weiss <martin.weiss1@gmx.de> wrote:
>
> <>
>
> What is " b[1,1]" in your first code segment? Sounds like you are referring
> to a -matrix- but I cannot see where it is actually defined.
>
>
> HTH
> Martin
>
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Mirko
> Sent: Montag, 5. April 2010 13:02
> To: statalist@hsphsun2.harvard.edu
> Subject: st: graph on marginal effects and confidence intervals
>
> Dear all,
>
> I would like to plot marginal effects (of interaction terms) with
> their confidence interval.
>
> Graphing marginal effects it is easy enough (although I am sure there
> are more efficient ways of doing this by using -mat- or something like
> that):
>
> sysuse auto, clear
> regress mpg i.foreign##c.weight i.rep78 headroom
> margins, dydx(weight) over(foreign) post
> gen x = _n in 1/3
> gen mem = b[1,1] in 1
> replace mem= b[1,2] in 2
> twoway (rscatter mem mem x), xlabel(1(1)2) yline(0)
>
> Confidence intervals could be add to that graph as bars by including
> -(rcap up low x)- to the -twoway- command; where up and low are upper
> and lower confidence intervals, respectively:
>
> twoway (rcap up low x) (rscatter mem mem x), xlabel(1(1)2) yline(0)
>
> The problem is how can I "capture" the confidence intervals from
> -margins- and generate up and low variables?
>
> Any suggestion would be greatly appreciated.
>
> Best wishes,
> Mirko
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```