Postestimation with tobit: predicting censored variable

[yulya truskinovsky]

I am using tobit to get a simple censored prediction of income using data from the American Community Survey. The data contain some negative values corresponding to negative income such as business losses. I want a censored prediction of income so I use the postextimation command predict, ystar() in the following way:

tobit faminc i.age4 i.education i.adults3 black other i.year, ll(0)
predict xb
predict ystar, ystar(0,.)

I have two questions
1) when I use the above specification including weights as provided by ACS ([aweight = perwt]) the distribution of censored predicted values is orders of magnitude above the actual distribution, with the same variance.
2) when I use the above specification as written, predict, ystar(0,.) is supposed to give me y* = 0 if xb + u < 0, however the predicted values are E(y*|y>0), and so seems to be censored above zero, so I end up with no zero predicted values, although my sample contains about 2% zeros.


I have found the following related discussion in the archive but I'm still stuck:

http://www.stata.com/statalist/archi.../msg00524.html

I am using Stata version 12. thank you very much for your help!

Yulya

[Steve Samuels]

This is the Sandbox forum, where people can try out posting features like Latex. Questions about Stata and statistics should go in the General Forum.