st: zero-inflated Tobit models

[Katie Farrin <kfarrin@gmail.com>]

Hi, Statalisters,

I'm working with data with left-censored values (at zero) and am thus
far using a Tobit model.  One of my professors mentioned a
zero-inflated Tobit versus a regular Tobit.  My dependent variable,
business profits, is censored at zero for survey respondents who do
not own any part of a private business.  However, for those who do
report business income (only about 1/5 of the sample), profits can be
negative.

First, I am wondering if there is a Stata program that performs
zero-inflated continuous data regressions.  I have not come across a
program that does zero-inflated Tobit.  Second, I was wondering if
anyone familiar with the models could give a brief explanation of the
advantages of a zero-inflated model compared to a standard Tobit; I
have read articles showing differences in parameter estimates using
the two types of models, but am a little confused about the
assumptions regarding the data generation process when I compare the
two models for my research.

Thanks in advance for the help!

Best,
Katie
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