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Re: st: Contract/Collapse Combination Continued


From   [email protected] (Brendan Halpin)
To   [email protected]
Subject   Re: st: Contract/Collapse Combination Continued
Date   Mon, 21 May 2012 23:04:17 +0100

On Mon, May 21 2012, Lucas wrote:

> So, my question was trying to see if one could contract/collapse the
> individual-level data to make it look like Brendan's data, and do so
> such that one line contained counts of both the ENTERCOLL=0 and
> ENTERCOLL=1 cases.

An ordinary collapse across all the variables (including ENTERCOLL) will
get you almost to my beginning format, except that you won't necessarily
have every pair. Here's a (non-tested!) sketch of a method of dealing
with pairs and singletons, assuming the variables are ordered as in your
example:

. // First a simple collapse
. gen n = 1
. collapse (sum) n, by(x1-entercoll)

. // Now deal with non-pairs
. sort x1-entercoll
. by x1-x15: gen nobs = _N

. // Create a duplicate for every singleton
. expand 2 if nobs==1

. // Edit the values in the duplicate accordingly
. by x1-x15: replace n=0 if nobs==1 & _n==1 & entercoll==1
. by x1-x15: replace n=0 if nobs==1 & _n==2 & entercoll==0

. // Now reduce the pairs to a single observation
. gen nno = n
. gen nyes = n[_n+1]
. keep if entercoll==0
. drop n entercoll


Brendan
-- 
Brendan Halpin,   Department of Sociology,   University of Limerick,   Ireland
Tel: w +353-61-213147  f +353-61-202569  h +353-61-338562;  Room F1-009 x 3147
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