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st: RE: creating variable with randomly missing values


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: creating variable with randomly missing values
Date   Thu, 6 Dec 2007 23:59:57 -0000

I will ignore "dropped" and focus on "recoded as missing value". 

In all solutions, before you do this, 

. set seed 280352 

or whatever, for reproducibility.  

This will do it approximately 

. replace x = . if uniform() < 0.5 

This will do it exactly 

. gen long id = _n 
. gen random = uniform()
. sort random 
. replace x = . in 1/2500
. sort id 

Ahmed Arif

I have a dataset with variables x and y. the dataset has 5000
observation. i want to generate another variable xmiss, such that 50%
of x values are dropped (recoded as missing value) randomly from the
dataset w/o affecting values of y. is there an easy way to do this?

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