Date:         Fri, 12 May 2006 21:08:57 -0500
Reply-To:     Jiann-Shiun Huang <Jiann-Shiun.Huang@AMERUS.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Jiann-Shiun Huang <Jiann-Shiun.Huang@AMERUS.COM>
Subject:      Re: Simple Event history, 'ever occur' question
Comments: To: mshall2@GMAIL.COM
Content-Type: text/plain; charset=US-ASCII

Matt:

  If your intermig indicates that there is an occurrence of
(interstate) migration in t or prior to t then try the following:

do i=2 to 48;
  if inter[i] eq 1 then do;
    do j=i to 48;
      intermig[j]=1;
    end;
    leave;
  end;
  else intermig[i]=0;
end;

  If this does not work for you, write back and provide more detail
infor and some sample dataset, if possible.

J S Huang
1-515-557-3987
fax 1-515-557-2422

>>> <mshall2@GMAIL.COM> 05/12/06 8:40 PM >>>
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