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Re: st: FW: How to keep only firms that have at least two consecutive years of data


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: FW: How to keep only firms that have at least two consecutive years of data
Date   Thu, 5 Jul 2012 16:06:58 +0100

In the light of this crucial detail my previous suggestion can be modified to

drop if missing(var1, var2, var3, var4, var5)
bysort id (year) : gen spacing = year - year[_n-1]
bysort id (spacing) : keep if spacing[1] == 1

On Thu, Jul 5, 2012 at 3:56 PM, umut senalp <uerksan@hotmail.com> wrote:

> Thank you for your reply, the thing is, all firms have 9 consecutive years of observation for the 5 variables but with missing. What I am trying to do is to keep only firms have observation for all the variables and have it at least two consecutive years. When I follow this
>  xtset id year
>> bys id: gen nyear=[_N]
>> keep if nyear>1 ,         this does not drop any observation at all, since all id's have 9 years data for the variables.

From: anees@aneconomist.com

>> Check this might help you.
>>
>> xtset id year
>> bys id: gen nyear=[_N]
>> keep if nyear>1

On Thu, Jul 5, 2012 at 7:04 PM, umut senalp <uerksan@hotmail.com> wrote:

>> > I have a panel of 1250 units (firms) and five variables (with missing values), for the time period of 2003 to 2011. I would like to keep only firms that have a minimum of 2 consecutive annual observations for all variables together. I would be glad if you could help me to write a code for it.

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