I am attempting to fit a model using xttobit, however, I cannot get xttobit to
fit with even the most basic model: log likelihood is "not concave."
I have 9040 observations and 89 groups, with a minimum of 1, a maximum of
1252, and an average of 101 observations per group.
There is no time variable in the model
The dependent variable is truncated at 0 and 20, with 5% at zero and about 8%
at 20.
It should be noted that for some of the groups there is little or no variation
on the dependent variable. There are at least 5 groups that have no variation
on the DV.
I have tried the following code:
xttobit aec rca, i(cnae) ll(0) ul(20)
xttobit - aec imp_pen p_m srca rca d_rca itt wage wt_unid polcon prod
polcon_prod, i(cnae) ll(0) ul(20)
and neither will converge after more than 400 iterations.
I have run - xtreg aec imp_pen p_m srca rca d_rca itt wage wt_unid polcon
prod polcon_prod, i(cnae)
and received what logical estimations for the coefficients and a rho of 0.48.
Any help would be greatly appreciated.
--
Anthony A. Pezzola
(02) 354-7823
Profesor de Ciencia Pol�tica
Instituto de Ciencia Pol�tica
Universidad Pontifica Cat�lica de Chile
Santiago de Chile
*
* 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/
