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st: RE: Filtering observations.. Urgent HELP


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Filtering observations.. Urgent HELP
Date   Mon, 29 Aug 2005 21:46:06 +0100

To get a count of missings in your two variables
you can go 

egen nmiss = rowmiss(dependencia reservas) 

or 

gen nmiss = mi(dependencia) + mi(reservas) 

Observations you want have no missing values. So 
-nmiss- is 0 and you can count such observations

bysort shcode : egen npresent = sum(nmiss == 0) 

Actually, that could all be telescoped into one: 

bysort shcode : egen npresent = sum(!mi(dependencia) + !mi(reservas)) 

Then you are interested in panels for which -npresent > 9-. 

Incidentally, see the advice on claiming urgency at 

http://www.catb.org/~esr/faqs/smart-questions.html#urgent

(This document is cited by the Statalist FAQ.) 

Nick 
n.j.cox@durham.ac.uk 

Alonso Viloria
 
> I am working with Panel data information. I am trying to 
> create a filter 
> to tell me Which individuals have complete information for a set of 
> variables AND just let me know which of them -individuals- 
> have more than 
> certain amount of observations. For example if a have data 
> for 10 years i 
> want stata to tell me which individuals have information of 
> the variables 
> in the same years AND only let me know those individuals that 
> have data 
> for more than 6 years.... Thanks for any pointers in the 
> subject. As you 
> can see i am rather a neophyte in the subject. As far as I 
> have gotten is: 
> by shcode: summarize reservas depeendencia if (reservas~=.) & 
> (dependencia~=.)
> 
> What i want to create is something like:
> by shcode: summarize reservas depeendencia if (reservas~=.) &
> (dependencia~=.) & (Number of Observations or periods in which i find
> both "dependencia" and "reservas" or matching datas are more 
> than 9 periods.

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