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Re: st: panel data-dropping all observations for the identifier when certain variable value is missing


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: panel data-dropping all observations for the identifier when certain variable value is missing
Date   Wed, 6 Jul 2011 08:28:27 +0100

bysort firmid (offdate) : drop if offdate[_N] < 2008

bysort firmid (offdate) : gen byte islast = _n == _N

list firmid offdate if islast

See also

SJ-2-1  pr0004  . . . . . . . . . . Speaking Stata:  How to move step by: step
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q1/02   SJ 2(1):86--102                                  (no commands)
        explains the use of the by varlist : construct to tackle
        a variety of problems with group structure, ranging from
        simple calculations for each of several groups to more
        advanced manipulations that use the built-in _n and _N

Nick

On Wed, Jul 6, 2011 at 1:07 AM, Sabrina Helmut <vitamint@hotmail.de> wrote:

> I have firm-year observations for the years 2003-2010. For cases where the last value for the variable <offdate>, which is a variable containing dates, is older than a
> date in 2008 (so date in 2007, 2006,...) then stata shall drop the firm/identifier at all, so for
> every year. Then, I want stata to show me for every firm/identifier the last entry for the variable <offdate>, which could then either be a date in 2008, 2009 or 2010. Which commands could help me doing this?
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