Hello, this is my first post here in the SAS forums!   I have a data set which requires a manipulation that I am unable to figure out how to do.   It's set up like this:   fruit               count           day apples          500                1 apples          300                3 apples          505                5 apples          487                7 oranges        36                 1 oranges        39                 5 oranges        42                 7 pears            17                 1 pears            16                 2 pears            13                 3 pears            21                 5 pears            27                 6   What I need to do is find the difference in number of fruit on each day from the first day. So for apples, I need to calculate the difference in # of apples between days 1 and 3, 1 and 5, 1 and 7. For oranges, days 1 and 5, 1 and 7, etc. The difference on each day will be stored in a new variable.   Can anyone help with this? Or provide suggestions? I do most of my work in R, and trying to do this in SAS is obviously not the same. ... View more