How do you define a new format in SAS?

Defining a new format in SAS is accomplished primarily through the PROC FORMAT procedure. This procedure allows users to create custom formats that can be applied to variables within datasets.

When using PROC FORMAT, you can specify how values of variables should be displayed. For instance, you can map numerical values to more meaningful text descriptions or group categories efficiently. The general syntax involves using the VALUE statement within PROC FORMAT to create these mappings. Once the format is defined, it can then be applied to variables in various procedures, enhancing data presentation and readability.

Other options mentioned in the question focus on different functions within SAS but do not specifically allow for the creation of new formats. Specifying formats in the DATA step refers to applying existing formats to variables rather than creating new ones. Including formats in the PROC PRINT statement allows for the use of predefined formats for display purposes but does not involve the creation of a new format. Modifying dataset attributes may include changing variable types or labels but does not pertain to the definition of formats.

Therefore, the correct answer, which involves using PROC FORMAT to define new formats, encapsulates the proper method for formatting in SAS.