That's why Jeph had the statement
drop if profit2 == .
except that I think it should have read
drop if profits3 == .
This will include only those observations that have a profit for this year & the following two. Per Nick's recommendation, you should also give some serious thought to gaps in profit data for a given firm.
Eric
p.s. Jeph, what is the meaning of HTH?
>But i dont want all the observations
>for example if a firm has observations for 1990-2004 the new database will
>have observations for 1990-2002. In the same way for a firm with data for
>1990-1995 will have observations for 1990-1993
>Thanks
>
>-----Original Message-----
>From: Jeph Herrin <[email protected]>
>To: [email protected]
>Date: Tue, 27 Jun 2006 10:17:23 -0400
>Subject: Re: st: superposed rolled windows
>
>> Try
>>
>> gen profits1=profits
>> bys firms (years): gen profits2=profits[_n+1]
>> bys firms (years): gen profits3=profits[_n+2]
>> drop if profit2==.
>>
>> HTH,
> > Jeph
>>
*
* 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/
