On Thu, 2 Sep 2010, Henrique Andrade wrote: > How can I accumulate a series in 12 months inside a script? Now this is what > I'm doing: > > series var112m = var1 + var1(-1) + var1(-2) + var1(-3) + var1(-4) + var1(-5) > + var1(-6) + var1(-7) + var1(-8) + var1(-9) + var1(-10) + var1(-11) > > Could you please suggest a more elegant way? # cumulate var1 series var1cum = cum(var1) # take the annual difference series var112m = var1cum - var1cum(-12) # and fill in the dropped observation var112m[12] = var1cum[12]