Building a longitudial data

park2039 — Thu, 31 Oct 2013 19:39:05 GMT

I am building a longitudial data for my study. The input data has id, year, event, and event year variables. I am trying to create a variable z which is time elapsed from the last event. Can someone show a data step that computes z? Thanks.

id year event event_yr z

1 1986 0 .

1 1987 0 .

1 1988 0 .

1 1989 0 .

1 1990 0 .

1 1991 0 .

1 1992 0 .

1 1993 0 .

1 1994 0 .

1 1995 0 .

1 1996 1 1996

1 1997 0 .

1 1998 0 .

1 1999 0 .

1 2000 0 .

1 2001 1 2001 5

1 2002 0 .

1 2003 0 .

1 2004 0 .

1 2005 0 .

1 2006 0 .

1 2007 0 .

1 2008 1 2008 7

1 2009 0 .

1 2010 0 .

1 2011 0 .

1 2012 0 .

2 2010 0 .

2 2011 1 2011 0

2 2012 0 .

3 2007 0 .

3 2008 1 2008 0

3 2009 1 2009 1

3 2010 0 .

3 2011 0 .

3 2012 1 2012 3

Re: Building a longitudial data

art297 — Fri, 01 Nov 2013 02:58:59 GMT

: Assuming your data are already sorted like in your example, and that you really want to assign a 0 for id eq 1 and event_yr eq 1996, then something like the following should suffice:

data want;

set have;

by id;

retain last_event;

if first.id then call missing(last_event);

if event eq 1 then do;

z=ifn(last_event gt 0,event_yr-last_event, 0);

last_event=event_yr;

end;

run;

topic Re: Building a longitudial data in SAS Programming

Building a longitudial data

Re: Building a longitudial data