Numeric length in SAS®: a case study in decision making

Abstract This paper discusses various factors to be considered when making decisions regarding the properties of stored data. These factors extend beyond properties of the data files to include the context within which the data are used. Decisions about the stored length of numeric variables in SAS® data sets are used as an example of the decision-making process. Although the LENGTH statement in SAS is simple to use, what's going on behind the scenes is more complex, especially with respect to numeric variables. Understanding what happens when you specify the length of a numeric variable is essential for making informed decisions. SAS stores the value of all numeric variables in floating-point representation. This paper begins with a brief, practical, overview of floating-point representation and how it relates to programming questions regarding length, precision, and efficient use of disk space. We will discuss situations where numeric length should not be reduced, even if the range of integer values on ...