st: Drop observations

["Vidya Mahambare" <MahambareV@Cardiff.ac.uk>]

Hello,
For panel data regression, I want to include only those firms which have
observations for at least for four consecutive years out of ten. I suppose I
have to use drop or keep command, but can't figure out how.

thanks
vidya

*
*   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/