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RE: st: RE: Unbalancing a panel data set with country pairs
From
Matei Frunzetti <[email protected]>
To
[email protected]
Subject
RE: st: RE: Unbalancing a panel data set with country pairs
Date
Sat, 22 Jan 2011 13:57:27 +0100
Zitat von Nick Cox <[email protected]>:
<sacrifice>
. search identifier
points you to useful information. In this case,
egen idnew = group(id1 id2), label
is one of the easiest solutions. There is also a miniature review of
possibilities at
SJ-7-4 dm0034 . . . Stata tip 52: Generating composite categorical
variables
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
N. J. Cox
Q4/07 SJ 7(4):582--583 (no
commands)
tip on how to generate categorical variables using
tostring and egen, group()
but the help to -egen- -- which I did refer you to earlier --
contains enough to solve this problem.
Nick
[email protected]
Matei Frunzetti
Thank you for your timely answer and excuse me for not being clear
enough: my main problem is that the country pairs have a single id for
each country, so i need to introduce a new id with its values being
unique identifiers for the respective country pairs such that i can
use by etc.
ex:
id1 id2 idnew var1 ...
cty1 cty2 pair1 234
cty2 cty1 pair2 456
I am aware that this must seem pretty banal but i simply cannot find a
thread or help that would adress this problem, I probably just don't
know where to look.
Zitat von Nick Cox <[email protected]>:
I assume that "country pair" defines a panel identifier.
Look at the help for -egen-, which gives you one way to start.
In terms of missings,
egen missing_in_obs = rowmiss(varlist)
egen missing_in_panel = total(missing_in_obs), by(panelid)
drop if missing_in_panel
In terms of not enough years, you don't quite say what the time
resolution of your data is. But assuming you have yearly
observations then
bysort panelid : drop if _N < 17
drops the short panels. If it's half-years, quarters, months, etc.
adjust as needed.
You need to plug in your own <varlist> and <panelid>.
The big concept you appear to be missing is that of working -by:-.
There is a tutorial at
SJ-2-1 pr0004 . . . . . . . . . . Speaking Stata: How to move
step by: step
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
N. J. Cox
Q1/02 SJ 2(1):86--102 (no
commands)
explains the use of the by varlist : construct to tackle
a variety of problems with group structure, ranging from
simple calculations for each of several groups to more
advanced manipulations that use the built-in _n and _N
Nick
[email protected]
Matei Frunzetti
I 'm working on a panel data set over 17 years. It's fairly unbalanced
und i need to drop all observations for country pairs that either lack
full length (as in years) or have missings in one of the independant
variables. The problem is that i have to delete all observations of
these country pairs for all years if only one or more variables have a
missing or if it is one or more years short. I ran into a dead end
trying to figure out how to imply the rest of the observations of a
"faulty" country pair into the drop command.
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