Dear Stata users,
I have an issue with the estimation of average partial effects after
-oprobit- using -margeff-. Here is what I am observing:
I run:
oprobit y x1 x2 x3
margeff
Then, I calculate manually the effect of a change in x1 (which is
continuous) in the first outcome category using the following steps:
oprobit y x1 x2 x3
predict xb if e(sample), xb
gen out1 = (-1*(_b[x1])) * (normalden(_b[/cut1]- xb))
sum out1
The calculated mean is the average partial effect of x1.
Now, when I compare the estimated APE from -margeff- with the above mean,
the manually estimated effect turns out to be more than two times bigger in
magnitude than the one provided by -margeff-.
I also changed the sample and repeated the procedure. The effects were still
substantially different (although this time the -margeff- provided effect
was larger).
I would appreciate any ideas or suggestions.
Best regards,
Simo Goshev
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