Date:         Tue, 3 Nov 2009 07:16:42 -0800
Reply-To:     Undo <vanessa.monro@CIGNA.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Undo <vanessa.monro@CIGNA.COM>
Organization: http://groups.google.com
Subject:      Cumulative subtract - easy for you, surely :-)
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset=ISO-8859-1

 Hello,
I've been trying to subtract pols_cancelling from the total (87249)
and then from previous row so I have a "descending" cumulative column
but I can't get it to subtract from the previous row, only from the
very top one. Could anyone help please?
So the column pols_remaining should actually show 87249, 87133, 86993,
86894 etc

The code I have done to get to this is at the bottom. Thanks very much
in advance.


TIME_TO_       pols_        pols_
  CANCEL     cancelling    remainin

     .             0         87249
     0           116         87133
     1           140         87109
     2            99         87150
     3           104         87145
     4           104         87145
     5           115         87134
     6           185         87064
     7           387         86862
     8           380         86869
     9           286         86963
    10           284         86965
    11           267         86982
    12           336         86913
    13           391         86858
    14           499         86750
    15           361         86888

data zzz;
set zz;
retain pols_remaining;
pols_remaining=87249;
by time_to_cancel;
if first.time_to_cancel then do;
pols_remaining=pols_remaining-pols_cancelling;end;
run;