Date:         Mon, 8 Sep 2008 09:56:14 -0700
Reply-To:     jn_mao@yahoo.com
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         jn mao <jn_mao@YAHOO.COM>
Subject:      Data processing problem
In-Reply-To:  <eedeb67f-13c6-4a23-b3db-d20bdb337c14@a70g2000hsh.googlegroups.com>
Content-Type: text/plain; charset=iso-8859-1

Hi SASLs,I have a large dataset. I need to calculate the duration by each two connected dates bydrug for each patient, then divided by NT. Only select the 2nd data of NT to divide duration. My data:ID  date  drugname NTaa  1/2/08   xx   10aa  2/1/08   xx   14aa  2/3/08   yy   11aa  3/1/08  xx   15aa  3/2/08  yy   16The data I want:ID  duration  drugname NT   NT_duraa   31     xx     14     14/31aa   28     xx     15     15/28aa   29     yy     16     16/29 The duration is the difference of two connented dates for the same drug.like drug xx first data:  31=2/1/08-1/1/08.Thanks much.Jane