Date:         Mon, 28 Jan 2002 09:59:36 -0800
Reply-To:     Yvette <hollied@OLIN.WUSTL.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Yvette <hollied@OLIN.WUSTL.EDU>
Organization: http://groups.google.com/
Subject:      deleting duplicates
Content-Type: text/plain; charset=ISO-8859-1

Hello all,

I am tryin to write a line (or two) of code that will allow my data to
read if if this observation minus the next observation does not equal
zero then put a '.'  Although I haven't been very successful.

I tried the if first.year command but it put missing variables for all
of my data beyond the first year.  I want it to perform this function
by both ID and year - by this I mean I won't it to put a missing value
when not the first obs for the firm and year.

For example:

if not first.year for 1990 1991 and 1992 then put varA = '.'

I realixe the syntax is not correct but this is what I am trying to
get at.

Any help would be greatly appreciated.