SAS Certification Prep Guide, 4th Edition

Creating and Modifying Variables

Accumulating Totals

To add the result of an expression to an accumulator variable, you can use a sum statement in your DATA step.

Syntax, sum statement: variable+expression; variable specifies the name of the accumulator variable. This variable must be numeric. The variable is automatically set to 0 before the first observation is read. The variable's value is retained from one DATA step execution to the next. expression is any valid SAS expression. Note: If the expression produces a missing value, the sum statement ignores it. The sum statement is one of the few SAS statements that do not begin with a keyword.

The sum statement adds the result of the expression that is on the ...