What is the purpose of the LENGTH statement?

The LENGTH statement is used specifically to set the length of a character variable in SAS. When you define a character variable, SAS allocates a default length, which may not be optimal for the data you intend to store. By using the LENGTH statement, you can explicitly specify how many bytes to allocate for that variable, which can help in limiting memory usage and ensuring efficient data storage.

For example, if a character variable is intended to store strings that are only a few characters long, setting the length appropriately means that unnecessary memory won’t be wasted. This statement does not affect numeric variables, as their storage is managed differently, and it directly influences how SAS interprets and stores string data.

Other options provided in the question do not describe the function of the LENGTH statement accurately. Defining the format of a variable relates to how data is presented rather than how much space it occupies, assigning a label pertains to giving a variable a descriptive name for clarity, and removing unnecessary variables is a process that typically involves a DROP or DELETE statement.