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Re: st: creating expanded records with indicator variables, where different ID's reside in the same rows


From   Jeph Herrin <junk@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: creating expanded records with indicator variables, where different ID's reside in the same rows
Date   Wed, 21 Oct 2009 13:54:22 -0400


How about create two files and merge

  preserve
  keep if !mi(A)
  ren A ID
  gen byte A=1
  sort ID
  save theAs
  restore
  keep if !mi(B)
  ren B ID
  gen byte B=1
  sort ID
  merge 1:1 ID using theAs
  replace A=0 if mi(A)
  replace B=0 if mi(B)

?

hth,
Jeph



Michael McCulloch wrote:
Hello,
I have a data structure that has been gathered as follows, where each cell contains the subject ID if A is true, and similarly for B. Therefore, for subject 5, I have A=yes and B=yes, whereas for subjects 6 and 11, only B=yes.

A    B
5    5
6    11

I'd like to transform the data structure such that each row would have ID, and indicator variables for A and B.
id    A    B
5    1    1
6    0    1
11    0    1

I've tried an approach like this, where I create indicator variables but A and B, but am not sure how to "expand" from the data structure where different ID's reside in the same rows.
    . gen id1=a
    . gen id2=b
    . gen aa=1 if a!=.
    . gen bb=1 if b!=.

It also looks like -reshape- is not suitable because different ID's reside in the same rows.
Any advice would be appreciated.



Michael McCulloch
Pine Street Foundation
124 Pine Street
San Anselmo, CA 94960-2674
tel:    415-407-1357
fax:     206-338-2391
mm@pinestreetfoundation.org






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