st: average marginals for ivprobit

[Chris Rohlfs <car@uchicago.edu>]

hi statalist,

i have two questions about average marginal effects.  any 
thoughts/suggestions would be very much appreciated.

1) does anybody here know how to compute average marginal effects & their 
standard errors for ivprobit estimates?  mfx appears to only present 
marginal effects for one observation at a time (i.e., not the average of 
_N different marginal effects).  and the user-created margeff does not 
support ivprobit.

2) is there an easy way to compute average marginal effects and their 
standard errors for nonlinear functions of regressors?  for instance, i'm 
running an ivprobit of y on x (using some instrument z) and i'd like to 
estimate the average of dy/d(x^2) for my _N observations & get the 
appropriate standard error.

thank you very much!
chris
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