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st: Margins after xtreg, fe
From 
 
natasha agarwal <[email protected]> 
To 
 
[email protected] 
Subject 
 
st: Margins after xtreg, fe 
Date 
 
Tue, 23 Aug 2011 17:33:35 +0100 
Dear All,
I am estimating the following model
xtreg lnrval lnk lnw lnvfdi efd fdi*efd y14-y18, fe vce(robust)
(efd drops out of the estimation as it is time-invariant)
And then I want to estimate the elasticity at the median of efd. So I estimate
 margins, eyex(lnvfdi) at((median) efd)
I get the following result
Average marginal effects                          Number of obs   =      38573
Model VCE    : Robust
Expression   : Linear prediction, predict()
ey/ex w.r.t. : lnvfdi
at           : efd             =       .2371 (median)
------------------------------------------------------------------------------
             |            Delta-method
             |      ey/ex   Std. Err.      z    P>|z|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
      lnvfdi |  (not estimable)
------------------------------------------------------------------------------
Can someone please explain me why do I get such an output?
Many thanks
Natasha
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