Oh, one more thing. I think you will need to sort the data by id before
the egen command. So, the commands would be:
gen dummy=1
sort id
by id: egen numobs=count(dummy)
keep if numobs==14
Sorry for that particular oversight; hope this helps.
Sam
---------- Forwarded message ----------
Date: Mon, 4 Oct 2004 00:14:15 -0700 (PDT)
From: SamL <[email protected]>
To: [email protected]
Cc: [email protected]
Subject: Re: st: data management help
How about this:
gen dummy=1
by id: egen numobs=count(dummy)
keep if numobs==14
COMMENTS
1) gen dummy = 1 is to get a variable that is 1 for every case
2) by id: egen . . . is to create a variable, named "numobs" that contains
the total number of cases for each id number.
3) keep . . . just saves only those cases that have observations in all 14
years.
Hope this helps.
Sam
On Mon, 4 Oct 2004, mnitkin wrote:
> Your assumptions about the data are correct.
>
> I tried your suggestion, but "duplicates" is not a valid command on my
> version of Stata. Is there a similar command that might work with pre
> 7.0 versions of Stata.
> Thanks for the help,
> Mindy
>
> Richard Williams wrote:
> > At 12:09 AM 10/4/2004 -0400, mnitkin wrote:
> >
> >> I have a data set with 131,000 firm observations over 14 years.
> >> Individual firms may be in the data set between 1 and 14 times. I want
> >> to keep only those firms that have observations for the entire 14 year
> >> period.
> >>
> >> I've tried all the tricks I know as well as a number of suggestions on
> >> the stata website, but I haven't had any luck.
> >
> >
> > Something like this might do it. Lets suppose you want to keep those
> > cases where the same id number occurs 14 times (i.e. there is a first
> > occurrence and then 13 "duplicates"). Lets further assume each firm has
> > a maximum of 1 record per year. Then,
> >
> > duplicates tag id, gen(nyears)
> > keep if nyears == 13
> >
> >
> > -------------------------------------------
> > Richard Williams, Notre Dame Dept of Sociology
> > OFFICE: (574)631-6668, (574)631-6463
> > FAX: (574)288-4373
> > HOME: (574)289-5227
> > EMAIL: [email protected]
> > WWW (personal): http://www.nd.edu/~rwilliam
> > WWW (department): http://www.nd.edu/~soc
> >
> > *
> > * 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/
>
*
* For searches and help try:
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