--- On Sun, 22/11/09, Celia Vera wrote:
> I am estimating a bivariate probit for a two-stage process
> in which the second event is observed conditional on the
> outcome of the first one (the first event is leaving the
> workforce (left) and the second event is returning to the
> workforce (ret). So, return only happens if the person left
> the workforce).
> I understand i have to use a biprobit model with partial
> observability.
> but the likelihood function never converges (it is not
> concave) in all the iterations.
The help file warns that this model often won't converge
and advises to use the -dificult- option. Alternatively
you could look at -heckprob-.
Hope this helps,
Maarten
--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany
http://www.maartenbuis.nl
--------------------------
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
