Date:         Fri, 12 May 2006 18:40:47 -0700
Reply-To:     mshall2@GMAIL.COM
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         mshall2@GMAIL.COM
Organization: http://groups.google.com
Subject:      Simple Event history, 'ever occur' question
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset="iso-8859-1"

I'm with working a large dataset (N=~220,000) that has observations for
48 months. I am computed a migration history, and I have already
established when a migration has occurred. I am trying create a
variable that indicates whether a migration occured any time in the
past. Here's an example (in long form) of what I want the data to look
like:

t is time, inter is occurence of (interstate) migration, and intermig
is the 'migrant' variable.

t     inter        intermig
1       0               0
2       0               0
3       1               1
5       0               1
6       0               1
7       0               1

Here's a portion of the code (the data is currently in wide form) I've
written so far, but the problem I'm running into is that a preceeding
ever migrant value of 0 will override subsequent values. Nobody can
move during the first month so the line ' intermig[1]=0' confirms this.

array intermig(48);   /*Inter mig occured at t or any t prior (t-k)*/
array inter {1:48} interstate_move1-interstate_move48;
intermig[1]=0;
do i=2 to 48;

        /*Interstate Migrants*/
        if inter[i] eq 1 then intermig[i]=1;
        if inter[i] ne 1 then intermig[i]=0;
        intermig[i]=intermig[i-1];

I realize this is a very novice question, but it's been bothering me
all evening. Thanks much for any help you can provide.

Matt Hall
Penn State