Hi SAS community, i would like to create a column to calculate the interval in days between each Purchase_Flg = 1 for each USER_ID_Hash. I've racked my brains but it seems like i've arrived at a standstill.    Methods i've tried would be to use it in a by statement with User_ID_Hash, I_Date, Purchase_Flg (of course after sorting them) to try to obtain first.XXX and last.XXX variables to see if i could define some where statements based on them but it does not seem to work. I'm not sure how to approach this in the right way and it'll be great if someone can somehow point me in the right direction. Appreciate the help. ... View more