st: dependent variable with zero mass point

[Kit Baum <baum@bc.edu>]

Francesca said

Thank you very much for your replies to my question. I apologise for not
having specified better how my dependent variable has been obtained.  
It is
just a growth rate of firms, calculated as (employees at time t -  
employees
at time t-1)/employees at time t-1. I have 15678 observations, of which
23.7%  are negative values, 39.2% are zeros and the remaining are  
positive
values



My colleague (and from the sound of it Francesca's countryman) Fabio  
Schiantarelli dealt with this problem in a paper in Rev. Econ. Stat.  
looking at plant-level investment data, which are similarly  
characterized by a large number of 'we didn't get any new machines  
this year'. Have a look at

http://ideas.repec.org/p/boc/bocoec/337.html

to which there is free access.

Kit

Kit Baum, Boston College Economics
http://ideas.repec.org/e/pba1.html
An Introduction to Modern Econometrics Using Stata:
http://www.stata-press.com/books/imeus.html


*
*   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/