What does the BY statement do in a SORT procedure?

The BY statement in a SORT procedure is used to identify the subgroup for arrangement, meaning it specifies one or more variables by which the dataset will be sorted. When you include a BY statement, the sorting process organizes data based on the values of the specified variables in a hierarchical manner. For instance, if you sort by "age" and then by "name," the data will first be arranged by age, and within each age group, it will be further sorted by name.

This functionality is essential when dealing with grouped data, as it ensures that the sort order reflects the intended organization according to specific variables of interest. By utilizing the BY statement effectively, you can facilitate more meaningful analysis, reporting, and presentation of the data.

The other options refer to actions that are not applicable to the SORT procedure in SAS. Random sorting, variable creation, and importing external data files are outside the scope of what the BY statement is designed to accomplish within the context of sorting operations.