Stata 11 help for sum() help sum() ------------------------------------------------------------------------------- Title [D] functions -- Functions Mathematical function sum(x) Domain: all real numbers and missing Range: -8e+307 to 8e+307 (excluding missing) Description: returns the running sum of x, treating missing values as zero. For example, following the command generate y=sum(x), the jth observation on y contains the sum of the first through jth observations on x. See [D] egen for an alternative sum function, total(), that produces a constant equal to the overall sum. Also see Manual: [D] functions Help: [D] functions, [D] functions (math functions)