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Re: st: dropping incomplete frequencies without 'missing' in panel data
From
Joerg Luedicke <[email protected]>
To
[email protected]
Subject
Re: st: dropping incomplete frequencies without 'missing' in panel data
Date
Wed, 13 Jul 2011 11:30:14 -0400
You could do the following:
bys hhnr: gen nyears=_N
drop if nyears<7
But consider that more often than not, you do not need a completely
balanced panel and dropping households that are not fully observed
over the entire period of 7 years can potentially induce some sort of
bias.
J.
On Wed, Jul 13, 2011 at 10:39 AM, Abdul <[email protected]> wrote:
> Dear List,
>
> I have a panel dataset and I wanted to drop those observations where
> the variable 'hhnr' is missing in some time periods. for example when
> hhnr is 6, it is only reported in 2001 and not in subsequent years,
> whereas when hhnr is 9, it is reported in all years from 2001 to 2007.
>
> hhnr year volumew valuew
> 6 2001 770 4585
> 9 2001 9374 91672
> 9 2002 13576 145520
> 9 2003 4720 44709
> 9 2004 3429 30254
> 9 2005 5589.25 43225.37
> 9 2006 4577.1 44175.56
> 9 2007 6079.05 74066.045
> 13 2001 1273 11399
> 13 2002 1705 15619
> 13 2003 1306 11060
> 13 2004 728 5823
> 13 2005 331.2 2930.16
> 13 2006 541.2 2900.175
> 13 2007 635.6 2910.115
> 14 2004 467 5893
> 14 2006 360 4548
> 14 2007 897.15 11333.995
> 14 2007 897.15 11333.995
> 18 2001 4308 37267
> 18 2002 1234 13419
>
> If those observations where hhnr is not there were reported as missing
> I could have used this FAQ:
> http://www.stata.com/support/faqs/data/dropmiss.html
> Unfortunately, they are just left out and I am unable to drop them
> despite many attmpts. I would appreciate if you either help me with a
> way to make them explicitly missing in this dataset or yet better if
> you konw a way to drop them and keep only those 'hhnrs' with complete
> frequency (reported in all years).
>
> Thanks,
> Abdul
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