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RE: st: Continues panel data


From   Ozgur Ozdemir <ozdemirozgur@hotmail.com>
To   Stata <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Continues panel data
Date   Tue, 15 Oct 2013 15:19:13 +0000

Hi Nick,

Data might start in any year but needs to be continuous until the last year. so I believe I sohuld use 

> bysort firmid (year) : gen diff = cond(_n == 1, 1, year - year[_n-1])

am I right.

However, i did not get the difference between above and below:

> bysort firmid (diff) : drop if diff[_N]> 1

Can you clarify please ?

kind regards
Ozgur Ozdemir



----------------------------------------
> Date: Tue, 15 Oct 2013 15:39:20 +0100
> Subject: Re: st: Continues panel data
> From: njcoxstata@gmail.com
> To: statalist@hsphsun2.harvard.edu
>
> There are various ways to do this, depending on your details.
>
> The simplest is where an ideal panel includes say 10 annual values in which case
>
> bysort firmid : drop if _N < 10
>
> removes incomplete panels. Modify for "any value of 10".
>
> Another is where panels may start and end in different years but gaps
> are not acceptable.
>
> bysort firmid (year) : gen diff = cond(_n == 1, 1, year - year[_n-1])
>
> calculates a value that should always be 1 and
>
> bysort firmid (diff) : drop if diff[_N]> 1
>
> will drop panels with any values of 2 or more.
>
> If neither matches your exact situation, please spell out what it is.
>
> See also
>
> http://www.stata.com/support/faqs/data-management/identifying-runs-of-consecutive-observations/
>
>
> Nick
> njcoxstata@gmail.com
>
>
> On 15 October 2013 13:46, Ozgur Ozdemir <ozdemirozgur@hotmail.com> wrote:
>> Hi,
>>
>> I have a panel data (firm Id, year, sales etc), but would like to remove if there are any gaps for a given firm. e.g If a firm does have a record in 2000, and 2002, but not in 2001, I would like to remove it,.
>>
>> Is there any way of doing this in Stata please?
>>
>> thanks, Ozgur
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