I need 90-day-total-sum / 90-day-total-n, with the 90 days for each line defined defined as int_begin to int_end I don't need anything less than the 90 days, although will want to be able to extend the code to apply to 180-day averaging period, etc. I couldn't get the macro to work to provide the data step lines. If it helps, i've listed the data in csv format below..sorry about that. Site,date,n,sum,int_begin,int_end Site1,1/1/2012,12,750.1,10/3/2011,1/1/2012 Site1,1/2/2012,12,180.6,10/4/2011,1/2/2012 Site1,1/3/2012,10,160.2,10/5/2011,1/3/2012 Site2,1/1/2012,11,230.2,10/3/2011,1/1/2012 Site2,1/2/2012,11,280.4,10/4/2011,1/2/2012 Site2,1/3/2012,11,250.2,10/5/2011,1/3/2012 Site3,1/1/2012,12,448.2,10/3/2011,1/1/2012 Site3,1/2/2012,12,315.5,10/4/2011,1/2/2012 Site3,1/3/2012,12,175.3,10/5/2011,1/3/2012
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