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Re: st: RE: Unbalancing a panel data set with country pairs

From   Matei Frunzetti <>
Subject   Re: st: RE: Unbalancing a panel data set with country pairs
Date   Fri, 21 Jan 2011 15:06:53 +0100

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.

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.

Thank you for your help

Zitat von Nick Cox <>:

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


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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