What function does the INPUT statement serve in a SAS DATA step?

The INPUT statement in a SAS DATA step is crucial for defining variables and reading data from an external source, such as a text file or an input dataset. When SAS processes data, the INPUT statement tells SAS how to interpret the data that is being read, specifying the formats and the order in which the variables appear. This enables the correct assignment of the input values to the corresponding variables in the SAS dataset.

For instance, if the data is comma-separated or fixed-format, the INPUT statement can be used to correctly parse these values and store them as variables in the resulting SAS dataset. This is fundamental in preparing and manipulating datasets effectively, as accurate variable definitions and data reading are essential for subsequent data analysis and processing.

In contrast, the other functions mentioned, such as outputting results, summarizing data, and sorting data, are accomplished through different SAS procedures and statements, rather than the INPUT statement itself. Thus, while those tasks are important in data handling, they fall outside the specific role of the INPUT statement.