I don't know why you are suddenly referring to roa --which I assume is return on assets-- but I don't see how this changes anything I have written. Why don't you include some code in your efforts to solicit help? It would be easier to decipher what you are looking for & what you have tried.
Eric
>But in roa1 i don`t need all the observations
>example for a firms with information of roa for 1990-2004 I only will have
>roa1 for 1990-2002 and for a firm with roa for 1990-1994 I`ll have have info
>for 1990-1992
>
>-----Original Message-----
>From: "Eric G. Wruck" <ewruck@econalytics.com>
>To: statalist@hsphsun2.harvard.edu
>Date: Tue, 27 Jun 2006 10:42:16 -0400
>Subject: Re: st: superposed rolled windows
>
>> 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 <junk@spandrel.net>
>> >To: statalist@hsphsun2.harvard.edu
>> >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/
>
>
>*
>* For searches and help try:
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>* http://www.stata.com/support/statalist/faq
>* http://www.ats.ucla.edu/stat/stata/
--
===================================================
Eric G. Wruck
Econalytics
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====================================================
*
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