RE: st: Warning convergence not achieved

["Santos Silva, J.M.C." <jmcss@essex.ac.uk>]

Dear Ebru,

The reason may simply be that the Tobit ML estimates do not exist for your
data set. This will happen, for example, if one of your regressors is a dummy
that is equal to one only when y is equal to zero. The problem, in a different but 
related context is discussed here:
http://www.sciencedirect.com/science/article/pii/S0165176510000832
http://www.stata-journal.com/article.html?article=st0225

A simple way to check for this is to run a probit instead of a Tobit, with the same
y and the same regressors, and see if you have a "perfect predictor".

Hope this helps,

Joao


> Dear All,
> 
> When I run the tobit estimation, sometimes it gives this warning "convergence 
> not achieved". What could be the reasons? and how can I deal with that?
> 
> Best wishes
> Ebru
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