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Re: st: dropping incomplete frequencies without 'missing' in panel data
From
Abdul <[email protected]>
To
[email protected]
Subject
Re: st: dropping incomplete frequencies without 'missing' in panel data
Date
Wed, 13 Jul 2011 17:43:09 +0200
Dear Joerg,
Thank you for the much needed help. your code worked as I wanted. I
will also remember the point about bias you raised. Thanks a lot
again.
Abdul
On Wed, Jul 13, 2011 at 5:30 PM, Joerg Luedicke
<[email protected]> wrote:
> 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
>> *
>> * For searches and help try:
>> * http://www.stata.com/help.cgi?search
>> * http://www.stata.com/support/statalist/faq
>> * http://www.ats.ucla.edu/stat/stata/
>>
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
--
Abdul
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/