Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: RE: How to add a records to panel data


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: How to add a records to panel data
Date   Tue, 19 Apr 2005 17:21:20 +0100

Comments on three levels: 

1. Don't do this. If you do this, you lock 
yourself into needing to exclude such records from 
most later analyses. Unless memory is a real 
issue, have a variable containing this 
information, i.e. store it in an extra column,
not extra rows. Even though values are repeated
for every observation in each panel, that is 
usually not a problem and indeed often helpful. 

So to get what you need, without changing 
the number of records, 

egen died = max(year), by(id) 
replace died = died + 1

2. If you don't accept my advice, you need
something like this: 

gen byte died = 0 
egen group = group(id) 
su group, meanonly 
qui forval g = 1/`r(max)' { 
	su year if group == `g', meanonly 
	expand 2 if group == `g' & year == r(max) 
	replace year = r(max) + 1 in l 
	replace died = 1 in l 
}
drop group 
sort id year 
edit id year died 
	
3. Really, don't do this. See #1.  

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

xiao yi
 
> I have an unbalanced panel data(cross-setion and
> time-series) which looks like below:
> 
> ID   year  x1   x2
> 1    1993  ..   ..
> 1    1994  ..   ..
> 1    1995  ..   ..
> 2    1995  ..   ..  
> 2    1996  ..   ..
> 2    1997  ..   ..
> 3    1993  ..   ..
> 3    1994  ..   ..
> 3    1995  ..   ..
> 
> The data is about firms' survival analysis. The last
> year of my sample is 2003. In the example above, firm
> 1 dies in 1996 because the last year of this firm
> is 1995 and firm 2 dies in 1998, and so on. I want to
> add a record at the end of each subject (firm)
> indicating the year when the fird dies. Can anyone
> tell me how to accomplish this? Thank you in advance.

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index