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

 From Nick Cox To "'statalist@hsphsun2.harvard.edu'" Subject st: RE: Unbalancing a panel data set with country pairs Date Fri, 21 Jan 2011 13:39:48 +0000

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

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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