Hi All, New SAS user here.  I have a panel data structure, from which I am trying to calculate the duration between observations.  My test data looks like this: ID     Enter Date     Exit Date     Sex     Age 1        1/1/2000       1/1/2002       m       24 1        5/5/2006        5/5/2009      m       30 1        8/8/2011        8/8/2013      m       35 2        2/2/2002        2/2/2005       f        42 2        6/6/2006        6/6/2010       f        46 3        3/3/2003        3/3/2004      m       19 3        4/4/2008        4/4/2012      m       24 I want to create a variable that subtracts the exit date from the next enter date, so that last observation for each ID group is missing.  Any efficient ways to do this without running loop? Thanks in Advance. ... View more