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st: RE: cleaning data efficiently


From   Nick Cox <n.j.cox@durham.ac.uk>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   st: RE: cleaning data efficiently
Date   Fri, 28 Oct 2011 16:24:43 +0100

1. -egen- has a -mode()- function. 

egen mode = mode(regionname), by(regioncode) 

2. 

For that you need something like 

egen tag = tag(mode regioncode) 
egen ndistinctvalues = total(tag), by(mode) 

See also for a review 

SJ-8-4  dm0042  . . . . . . . . . . . .  Speaking Stata: Distinct observations
        (help distinct if installed)  . . . . . .  N. J. Cox and G. M. Longton
        Q4/08   SJ 8(4):557--568
        shows how to answer questions about distinct observations
        from first principles; provides a convenience command

3. 

ssc inst groups 
help groups
groups regionname regioncode 

(there are other ways, but I like this one)

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

Vitorino, Maria Ana

Suppose I have the following data:

regioncode  regionname
X  AAA
Y BBB
Z CCC
X   .
X AAA
Y BBB
Z   .
Z AAA
Z CCC
Z CCC

Assume also that the regioncode variable is correct but there are some errors and missing values in the regionname variable.
1) Is there an efficient way to fix the entries in the regionname variable? (For this we need to assume that the correspondence between regioncode and regioname that occurs more frequently is the correct one.)

I usually deal with this type of issues using several lines of code so I'm wondering if there is a more efficient way making use of some stata commands that I'm not familiar with.

Also, if, after correcting the mistakes, I want to 
2)check if the correspondence between the two variables is unique 
3) create a table with regionname regioncode and frequency of observations (but not a two-way table)
What is the most efficient way?

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