How can you create a new variable in a DATA step?

Creating a new variable in a DATA step is accomplished through the use of an assignment statement that employs the equal sign (=). This method allows you to define a new variable and assign it a value based on calculations, existing variables, or constants.

Within the DATA step, the syntax typically looks like this:

data new_dataset;

set existing_dataset;

new_variable = existing_variable + 10; /* Example of creating a new variable */

run;

In this example, 'new_variable' is created by taking the value of 'existing_variable' and adding 10 to it. The assignment statement facilitates manipulation of data as it flows through each iteration of the DATA step.

The other methods listed do not directly create new variables. For instance, the SET statement retrieves variables from an existing dataset but does not create new variables in itself. Similarly, the INPUT statement is used for reading data into a dataset but does not create new variables without an assignment context. Using the PROC step is primarily for data analysis and reporting rather than for creating or managing variables within a dataset directly. Thus, the most straightforward and appropriate way to create a new variable is indeed using an assignment statement with the equal sign.