st: problem with _diparm, conformability error

[Antoine Terracol <Antoine.Terracol@univ-paris1.fr>]

Dear statalisters,

I have a multiple equation ml model from which I wish to calculate 
standard errors for various functions of the parameters.

When I try to use _diparm to evaluate the sum of two parameters, one 
being the constant of an equation (duree1) containing other variables, 
and the other is a constant from a constant-only equation (mass1), I get 
the following error message:

. _diparm duree1 mass1, f(@1+@2) d(1 1)
conformability error
r(503);


If, however, I try to sum two constants from constant-only equations, it 
all works fine:


. _diparm mass1 mass2, f(@1+@2) d(1 1) prob label("sum")
  sum |   7.123457   1.241295     5.74   0.000     4.690564     9.55635


applying standard transformation to [duree1][_cons] also works fine:

. _diparm duree1, exp prob
/duree1 |   .0022996   .0019432     1.18   0.237     .0004389     .012049


I can't figure out what is wrong with my first example.

Antoine



--
Ce message a ete verifie par MailScanner
pour des virus ou des polluriels et rien de
suspect n'a ete trouve.

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/