--- Ali Khashan wrote:
I have a large dataset similar to this:
mother_number child_number GA nDate suggested var
1234567891 23456789 35 21 Feb 1975 .
1234567891 23456781 37 30 May 1978 35
1234567891 23456782 40 04 Oct 1982 37
1234567892 56789012 37 17 Mar 1976
1234567893 56489023 40 23 Sep 1985
1234567894 34567891 40 19 Nov 1977
1234567894 45567890 42 13 May 1979
From mother_number you can see that some women have more than one
child (they
have the same identification number). GA is gestational age and
nDate is date
of birth of the child. I need to generate another variable which indicates
gestational age of the previuos child.
*---------------------- begin example ------------
clear
input double mother_number double child_number GA
1234567891 23456789 35
1234567891 23456781 37
1234567891 23456782 40
1234567892 56789012 37
1234567893 56489023 40
1234567894 34567891 40
1234567894 45567890 42
end
bys mother_number (GA): gen prevGA = GA[_n-1]
list
*-------------------- end example -------------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
*
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