Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: data management help


From   SamL <saml@demog.berkeley.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: data management help
Date   Mon, 4 Oct 2004 00:14:15 -0700 (PDT)

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:  Richard.A.Williams.5@ND.Edu
> > 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:
> *   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:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index