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Re: st: Dropping/Keeping observations

From   Maarten buis <>
Subject   Re: st: Dropping/Keeping observations
Date   Sat, 22 Apr 2006 13:55:40 +0100 (BST)

The example below might do something like what you want. Assuem that rep78 is your id (with the
added observation created in the second line which should be dropped). _n is the current
observation number, while _N is the total number of observations in the category defined by -by-.
so -if _n==_N- means the last observation in that category, -_N>1- means if that category has more
than one observation, and rep78<. ensures that you only take nonmissing values of rep78.

*---------begin example------------
sysuse auto, clear
replace rep78 = 10 in 10 /*create a unique value in rep78*/
sort rep78
list rep78 in 1/10
by rep78: keep if _n==_N & _N>1 & rep78 <.
list rep78
*----------end example--------------

--- Gauri Khanna <> wrote:
> I would like to KEEP those plots/observations 
> where farmerID appears more than once. Hence, I would like to DROP those 
> observations which have only one farmerID. Any tips?

Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting adress:
Buitenveldertselaan 3 (Metropolitan), room Z214

+31 20 5986715

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