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CHAPTER 3 Working with Your Data 3.1 Creating and Redefining Variables 78 3.2 Using SAS Functions 80 3.3 Selected SAS Character Functions 82 3.4 Selected SAS Numeric Functions 84 3.5 Using IF-THEN Statements 86 3.6 Grouping Observations with IF-THEN/ELSE Statements 88 3.7 Subsetting Your Data 90 3.8 Working with SAS Dates 92 3.9 Selected Date Informats, Functions, and Formats 94 3.10 Using the RETAIN and Sum Statements 96 3.11 Simplifying Programs with Arrays 98 3.12 Using Shortcuts for Lists of Variable Names 100 78 The Little SAS Book 3.1 Creating and Redefining Variables If someone were to compile a list of the most popular things to do with SAS software, creating and redefining variables would surely be near the top. Fortunately, SAS is flexible and uses a common sense approach to these tasks. You create and redefine variables with assignment statements using this basic form: variable = expression; On the left side of the equal sign is a variable name, either new or old. On the right side of the equal sign may appear a constant, another variable, or a mathematical expression. Here are examples of these basic types of assignment statements: Type of expression Assignment statement numeric constant Qwerty = 10; character constant Qwerty = ten; a variable Qwerty = OldVar; addition Qwerty = OldVar + 10; subtraction Qwerty = O